Cutis

Dupilumab is a fully humanized monoclonal antibody to the α subunit of the IL-4 receptor that inhibits the action of helper T cell (T_H2)–type cytokines IL-4 and IL-13. Dupilumab was approved by the US Food and Drug Administration (FDA) in 2017 for the treatment of moderate to severe atopic dermatitis (AD). We report 2 patients with AD who were treated with dupilumab and subsequently developed facial flushing after consuming alcohol.

Case Report

Patient 1
A 24-year-old woman presented to the dermatology clinic with a lifelong history of moderate to severe AD. She had a medical history of asthma and seasonal allergies, which were treated with fexofenadine and an inhaler, as needed. The patient had an affected body surface area of approximately 70% and had achieved only partial relief with topical corticosteroids and topical calcineurin inhibitors.

Because her disease was severe, the patient was started on dupilumab at FDA-approved dosing for AD: a 600-mg subcutaneous (SC) loading dose, followed by 300 mg SC every 2 weeks. She reported rapid skin clearance within 2 weeks of the start of treatment. Her course was complicated by mild head and neck dermatitis.

Seven months after starting treatment, the patient began to acutely experience erythema and warmth over the entire face that was triggered by drinking alcohol (Figure). Before starting dupilumab, she had consumed alcohol on multiple occasions without a flushing effect. This new finding was distinguishable from her facial dermatitis. Onset was within a few minutes after drinking alcohol; flushing self-resolved in 15 to 30 minutes. Although diffuse, erythema and warmth were concentrated around the jawline, eyebrows, and ears and occurred every time the patient drank alcohol. Moreover, she reported that consumption of hard (ie, distilled) liquor, specifically tequila, caused a more severe presentation. She denied other symptoms associated with dupilumab.

Comment

Two other single-patient case reports have discussed similar findings of alcohol-induced flushing associated with dupilumab.^1,2 Both of those patients—a 19-year-old woman and a 26-year-old woman—had not experienced flushing before beginning treatment with dupilumab for AD. Both experienced onset of facial flushing months after beginning dupilumab even though both had consumed alcohol before starting dupilumab, similar to the cases presented here. One patient had a history of asthma; the other had a history of seasonal and environmental allergies.

Possible Mechanism of Action
Acute alcohol ingestion causes dermal vasodilation of the skin (ie, flushing).³ A proposed mechanism is that flushing results from direct action on central vascular-control mechanisms. This theory results from observations that individuals with quadriplegia lack notable ethanol-induced vasodilation, suggesting that ethanol has a central neural site of action.Although some research has indicated that ethanol might induce these effects by altering the action of certain hormones (eg, angiotensin, vasopressin, and catecholamines), the precise mechanism by which ethanol alters vascular function in humans remains unexplained.³

Deficiencies in alcohol dehydrogenase (ADH), aldehyde dehydrogenase 2, and certain cytochrome P450 enzymes also might contribute to facial flushing. People of Asian, especially East Asian, descent often respond to an acute dose of ethanol with symptoms of facial flushing—predominantly the result of an elevated blood level of acetaldehyde caused by an inherited deficiency of aldehyde dehydrogenase 2,⁴ which is downstream from ADH in the metabolic pathway of alcohol. The major enzyme system responsible for metabolism of ethanol is ADH; however, the cytochrome P450–dependent ethanol-oxidizing system—including major CYP450 isoforms CYP3A, CYP2C19, CYP2C9, CYP1A2, and CYP2D6, as well as minor CYP450 isoforms, such as CYP2E1— also are involved, to a lesser extent.⁵

A Role for Dupilumab?
A recent pharmacokinetic study found that dupilumab appears to have little effect on the activity of the major CYP450 isoforms. However, the drug’s effect on ADH and minor CYP450 minor isoforms is unknown. Prior drug-drug interaction studies have shown that certain cytokines and cytokine modulators can markedly influence the expression, stability, and activity of specific CYP450 enzymes.⁶ For example, IL-6 causes a reduction in messenger RNA for CYP3A4 and, to a lesser extent, for other isoforms.⁷ Whether dupilumab influences enzymes involved in processing alcohol requires further study.

Conclusion

We describe 2 cases of dupilumab-induced facial flushing after alcohol consumption. The mechanism of this dupilumab-associated flushing is unknown and requires further research.

Dupilumab is a fully humanized monoclonal antibody to the α subunit of the IL-4 receptor that inhibits the action of helper T cell (T_H2)–type cytokines IL-4 and IL-13. Dupilumab was approved by the US Food and Drug Administration (FDA) in 2017 for the treatment of moderate to severe atopic dermatitis (AD). We report 2 patients with AD who were treated with dupilumab and subsequently developed facial flushing after consuming alcohol.

Case Report

Patient 1
A 24-year-old woman presented to the dermatology clinic with a lifelong history of moderate to severe AD. She had a medical history of asthma and seasonal allergies, which were treated with fexofenadine and an inhaler, as needed. The patient had an affected body surface area of approximately 70% and had achieved only partial relief with topical corticosteroids and topical calcineurin inhibitors.

Because her disease was severe, the patient was started on dupilumab at FDA-approved dosing for AD: a 600-mg subcutaneous (SC) loading dose, followed by 300 mg SC every 2 weeks. She reported rapid skin clearance within 2 weeks of the start of treatment. Her course was complicated by mild head and neck dermatitis.

Seven months after starting treatment, the patient began to acutely experience erythema and warmth over the entire face that was triggered by drinking alcohol (Figure). Before starting dupilumab, she had consumed alcohol on multiple occasions without a flushing effect. This new finding was distinguishable from her facial dermatitis. Onset was within a few minutes after drinking alcohol; flushing self-resolved in 15 to 30 minutes. Although diffuse, erythema and warmth were concentrated around the jawline, eyebrows, and ears and occurred every time the patient drank alcohol. Moreover, she reported that consumption of hard (ie, distilled) liquor, specifically tequila, caused a more severe presentation. She denied other symptoms associated with dupilumab.

Comment

Two other single-patient case reports have discussed similar findings of alcohol-induced flushing associated with dupilumab.^1,2 Both of those patients—a 19-year-old woman and a 26-year-old woman—had not experienced flushing before beginning treatment with dupilumab for AD. Both experienced onset of facial flushing months after beginning dupilumab even though both had consumed alcohol before starting dupilumab, similar to the cases presented here. One patient had a history of asthma; the other had a history of seasonal and environmental allergies.

Possible Mechanism of Action
Acute alcohol ingestion causes dermal vasodilation of the skin (ie, flushing).³ A proposed mechanism is that flushing results from direct action on central vascular-control mechanisms. This theory results from observations that individuals with quadriplegia lack notable ethanol-induced vasodilation, suggesting that ethanol has a central neural site of action.Although some research has indicated that ethanol might induce these effects by altering the action of certain hormones (eg, angiotensin, vasopressin, and catecholamines), the precise mechanism by which ethanol alters vascular function in humans remains unexplained.³

Deficiencies in alcohol dehydrogenase (ADH), aldehyde dehydrogenase 2, and certain cytochrome P450 enzymes also might contribute to facial flushing. People of Asian, especially East Asian, descent often respond to an acute dose of ethanol with symptoms of facial flushing—predominantly the result of an elevated blood level of acetaldehyde caused by an inherited deficiency of aldehyde dehydrogenase 2,⁴ which is downstream from ADH in the metabolic pathway of alcohol. The major enzyme system responsible for metabolism of ethanol is ADH; however, the cytochrome P450–dependent ethanol-oxidizing system—including major CYP450 isoforms CYP3A, CYP2C19, CYP2C9, CYP1A2, and CYP2D6, as well as minor CYP450 isoforms, such as CYP2E1— also are involved, to a lesser extent.⁵

A Role for Dupilumab?
A recent pharmacokinetic study found that dupilumab appears to have little effect on the activity of the major CYP450 isoforms. However, the drug’s effect on ADH and minor CYP450 minor isoforms is unknown. Prior drug-drug interaction studies have shown that certain cytokines and cytokine modulators can markedly influence the expression, stability, and activity of specific CYP450 enzymes.⁶ For example, IL-6 causes a reduction in messenger RNA for CYP3A4 and, to a lesser extent, for other isoforms.⁷ Whether dupilumab influences enzymes involved in processing alcohol requires further study.

Conclusion

We describe 2 cases of dupilumab-induced facial flushing after alcohol consumption. The mechanism of this dupilumab-associated flushing is unknown and requires further research.

Dupilumab is a fully humanized monoclonal antibody to the α subunit of the IL-4 receptor that inhibits the action of helper T cell (T_H2)–type cytokines IL-4 and IL-13. Dupilumab was approved by the US Food and Drug Administration (FDA) in 2017 for the treatment of moderate to severe atopic dermatitis (AD). We report 2 patients with AD who were treated with dupilumab and subsequently developed facial flushing after consuming alcohol.

Case Report

Patient 1
A 24-year-old woman presented to the dermatology clinic with a lifelong history of moderate to severe AD. She had a medical history of asthma and seasonal allergies, which were treated with fexofenadine and an inhaler, as needed. The patient had an affected body surface area of approximately 70% and had achieved only partial relief with topical corticosteroids and topical calcineurin inhibitors.

Because her disease was severe, the patient was started on dupilumab at FDA-approved dosing for AD: a 600-mg subcutaneous (SC) loading dose, followed by 300 mg SC every 2 weeks. She reported rapid skin clearance within 2 weeks of the start of treatment. Her course was complicated by mild head and neck dermatitis.

Seven months after starting treatment, the patient began to acutely experience erythema and warmth over the entire face that was triggered by drinking alcohol (Figure). Before starting dupilumab, she had consumed alcohol on multiple occasions without a flushing effect. This new finding was distinguishable from her facial dermatitis. Onset was within a few minutes after drinking alcohol; flushing self-resolved in 15 to 30 minutes. Although diffuse, erythema and warmth were concentrated around the jawline, eyebrows, and ears and occurred every time the patient drank alcohol. Moreover, she reported that consumption of hard (ie, distilled) liquor, specifically tequila, caused a more severe presentation. She denied other symptoms associated with dupilumab.

Comment

Two other single-patient case reports have discussed similar findings of alcohol-induced flushing associated with dupilumab.^1,2 Both of those patients—a 19-year-old woman and a 26-year-old woman—had not experienced flushing before beginning treatment with dupilumab for AD. Both experienced onset of facial flushing months after beginning dupilumab even though both had consumed alcohol before starting dupilumab, similar to the cases presented here. One patient had a history of asthma; the other had a history of seasonal and environmental allergies.

Possible Mechanism of Action
Acute alcohol ingestion causes dermal vasodilation of the skin (ie, flushing).³ A proposed mechanism is that flushing results from direct action on central vascular-control mechanisms. This theory results from observations that individuals with quadriplegia lack notable ethanol-induced vasodilation, suggesting that ethanol has a central neural site of action.Although some research has indicated that ethanol might induce these effects by altering the action of certain hormones (eg, angiotensin, vasopressin, and catecholamines), the precise mechanism by which ethanol alters vascular function in humans remains unexplained.³

Deficiencies in alcohol dehydrogenase (ADH), aldehyde dehydrogenase 2, and certain cytochrome P450 enzymes also might contribute to facial flushing. People of Asian, especially East Asian, descent often respond to an acute dose of ethanol with symptoms of facial flushing—predominantly the result of an elevated blood level of acetaldehyde caused by an inherited deficiency of aldehyde dehydrogenase 2,⁴ which is downstream from ADH in the metabolic pathway of alcohol. The major enzyme system responsible for metabolism of ethanol is ADH; however, the cytochrome P450–dependent ethanol-oxidizing system—including major CYP450 isoforms CYP3A, CYP2C19, CYP2C9, CYP1A2, and CYP2D6, as well as minor CYP450 isoforms, such as CYP2E1— also are involved, to a lesser extent.⁵

A Role for Dupilumab?
A recent pharmacokinetic study found that dupilumab appears to have little effect on the activity of the major CYP450 isoforms. However, the drug’s effect on ADH and minor CYP450 minor isoforms is unknown. Prior drug-drug interaction studies have shown that certain cytokines and cytokine modulators can markedly influence the expression, stability, and activity of specific CYP450 enzymes.⁶ For example, IL-6 causes a reduction in messenger RNA for CYP3A4 and, to a lesser extent, for other isoforms.⁷ Whether dupilumab influences enzymes involved in processing alcohol requires further study.

Conclusion

We describe 2 cases of dupilumab-induced facial flushing after alcohol consumption. The mechanism of this dupilumab-associated flushing is unknown and requires further research.

Practice Gap

It is well established that surgical complications and a poor scar outcome can have a remarkable impact on patient satisfaction.¹ A common complication following dermatologic surgery is suture spitting, in which a buried suture is extruded through the skin surface. When repairing a cutaneous defect following dermatologic surgery, absorbable or nonabsorbable sutures are placed under the skin surface to approximate wound edges, eliminate dead space, and reduce tension on the edges of the wound, improving the cosmetic outcomes.

Absorbable sutures constitute most buried sutures in cutaneous surgery and can be made of natural or synthetic fibers.² Absorbable sutures made from synthetic fibers are degraded by hydrolysis, in which water breaks down polymer chains of the suture filament. Natural absorbable sutures are composed of mammalian collagen; they are broken down by the enzymatic process of proteolysis.

Tensile strength is lost long before a suture is fully absorbed. Although synthetic fibers have, in general, higher tensile strength and generate less tissue inflammation, they take much longer to absorb.² During absorption, in some cases, a buried suture is pushed to the surface and extrudes along the wound edge or scar, which is known as spitting³ (Figure 1).

The Technique

Choice of suture material for buried sutures can influence the risk of spitting.

Factors Impacting Increased Spitting
The 3 most common absorbable sutures in dermatologic surgery include poliglecaprone 25, polyglactin 910, and polydioxanone; of them, polyglactin 910 has been found to have a higher rate of spitting than poliglecaprone 25 and polydioxanone.² However, because complete absorption of polydioxanone can take as long as 8 months, this suture might “spit” much later than polyglactin 910 or poliglecaprone 25, which typically are fully hydrolyzed by 3 and 4 months, respectively.² Placing sutures superficially in the dermis has been found to increase the rate of spitting.⁵ Throwing more knots per closure also has been found to increase the rate of spitting.⁵

How to Decrease Spitting
Careful choice of suture material and proper depth of suture placement might decrease the risk for spitting in dermatologic surgery. Furthermore, if polyglactin 910 or a long-lasting suture is to be used, sutures should be placed deeply.

What to Do If Sutures Spit
When a suture has begun to spit, the extruding foreign material needs to be removed and the surgical site assessed for infection or abscess. Exposed suture material typically can be removed with forceps without local anesthesia. In some cases, fine-tipped Bishop-Harmon tissue forceps or jewelers forceps might be required.

If the suture cannot be removed completely, it should be trimmed as short as possible. This can be accomplished by pulling on the exposed end of the suture, tenting the skin, and trimming it as close as possible to the surface. Once the foreign material is removed, assessment for signs of infection is paramount.

How to Manage Infection—Postoperative infection associated with a spitting suture can take the form of a periwound cellulitis or stitch abscess.³ A stitch abscess can reflect a sterile inflammatory response to the buried suture or a true infection⁴; the former is more common.³ In the event of an infected stitch abscess, provide warm compresses, obtain specimens for culture, and prescribe antibiotics after the spitting suture has been removed. Incision and drainage also might be required if notable fluctuance is present.

It is crucial for dermatologic surgeons to identify and manage these complications. Figure 2 illustrates an algorithmic approach to managing spitting sutures.

Practical Implications

Spitting sutures are a common occurrence following dermatologic surgery that can lead to remarkable patient distress. Fortunately, in the absence of superimposed infection, spitting sutures have not been shown to worsen outcomes of healing and scarring.⁵ Nevertheless, it is important to identify and appropriately treat this common complication. The simple algorithm we provide (Figure 2) aids in cutaneous surgery by providing a straightforward approach to managing spitting sutures and their complications.

Practice Gap

It is well established that surgical complications and a poor scar outcome can have a remarkable impact on patient satisfaction.¹ A common complication following dermatologic surgery is suture spitting, in which a buried suture is extruded through the skin surface. When repairing a cutaneous defect following dermatologic surgery, absorbable or nonabsorbable sutures are placed under the skin surface to approximate wound edges, eliminate dead space, and reduce tension on the edges of the wound, improving the cosmetic outcomes.

Absorbable sutures constitute most buried sutures in cutaneous surgery and can be made of natural or synthetic fibers.² Absorbable sutures made from synthetic fibers are degraded by hydrolysis, in which water breaks down polymer chains of the suture filament. Natural absorbable sutures are composed of mammalian collagen; they are broken down by the enzymatic process of proteolysis.

Tensile strength is lost long before a suture is fully absorbed. Although synthetic fibers have, in general, higher tensile strength and generate less tissue inflammation, they take much longer to absorb.² During absorption, in some cases, a buried suture is pushed to the surface and extrudes along the wound edge or scar, which is known as spitting³ (Figure 1).

The Technique

Choice of suture material for buried sutures can influence the risk of spitting.

Factors Impacting Increased Spitting
The 3 most common absorbable sutures in dermatologic surgery include poliglecaprone 25, polyglactin 910, and polydioxanone; of them, polyglactin 910 has been found to have a higher rate of spitting than poliglecaprone 25 and polydioxanone.² However, because complete absorption of polydioxanone can take as long as 8 months, this suture might “spit” much later than polyglactin 910 or poliglecaprone 25, which typically are fully hydrolyzed by 3 and 4 months, respectively.² Placing sutures superficially in the dermis has been found to increase the rate of spitting.⁵ Throwing more knots per closure also has been found to increase the rate of spitting.⁵

How to Decrease Spitting
Careful choice of suture material and proper depth of suture placement might decrease the risk for spitting in dermatologic surgery. Furthermore, if polyglactin 910 or a long-lasting suture is to be used, sutures should be placed deeply.

What to Do If Sutures Spit
When a suture has begun to spit, the extruding foreign material needs to be removed and the surgical site assessed for infection or abscess. Exposed suture material typically can be removed with forceps without local anesthesia. In some cases, fine-tipped Bishop-Harmon tissue forceps or jewelers forceps might be required.

If the suture cannot be removed completely, it should be trimmed as short as possible. This can be accomplished by pulling on the exposed end of the suture, tenting the skin, and trimming it as close as possible to the surface. Once the foreign material is removed, assessment for signs of infection is paramount.

How to Manage Infection—Postoperative infection associated with a spitting suture can take the form of a periwound cellulitis or stitch abscess.³ A stitch abscess can reflect a sterile inflammatory response to the buried suture or a true infection⁴; the former is more common.³ In the event of an infected stitch abscess, provide warm compresses, obtain specimens for culture, and prescribe antibiotics after the spitting suture has been removed. Incision and drainage also might be required if notable fluctuance is present.

It is crucial for dermatologic surgeons to identify and manage these complications. Figure 2 illustrates an algorithmic approach to managing spitting sutures.

Practical Implications

Spitting sutures are a common occurrence following dermatologic surgery that can lead to remarkable patient distress. Fortunately, in the absence of superimposed infection, spitting sutures have not been shown to worsen outcomes of healing and scarring.⁵ Nevertheless, it is important to identify and appropriately treat this common complication. The simple algorithm we provide (Figure 2) aids in cutaneous surgery by providing a straightforward approach to managing spitting sutures and their complications.

Practice Gap

It is well established that surgical complications and a poor scar outcome can have a remarkable impact on patient satisfaction.¹ A common complication following dermatologic surgery is suture spitting, in which a buried suture is extruded through the skin surface. When repairing a cutaneous defect following dermatologic surgery, absorbable or nonabsorbable sutures are placed under the skin surface to approximate wound edges, eliminate dead space, and reduce tension on the edges of the wound, improving the cosmetic outcomes.

Absorbable sutures constitute most buried sutures in cutaneous surgery and can be made of natural or synthetic fibers.² Absorbable sutures made from synthetic fibers are degraded by hydrolysis, in which water breaks down polymer chains of the suture filament. Natural absorbable sutures are composed of mammalian collagen; they are broken down by the enzymatic process of proteolysis.

Tensile strength is lost long before a suture is fully absorbed. Although synthetic fibers have, in general, higher tensile strength and generate less tissue inflammation, they take much longer to absorb.² During absorption, in some cases, a buried suture is pushed to the surface and extrudes along the wound edge or scar, which is known as spitting³ (Figure 1).

The Technique

Choice of suture material for buried sutures can influence the risk of spitting.

Factors Impacting Increased Spitting
The 3 most common absorbable sutures in dermatologic surgery include poliglecaprone 25, polyglactin 910, and polydioxanone; of them, polyglactin 910 has been found to have a higher rate of spitting than poliglecaprone 25 and polydioxanone.² However, because complete absorption of polydioxanone can take as long as 8 months, this suture might “spit” much later than polyglactin 910 or poliglecaprone 25, which typically are fully hydrolyzed by 3 and 4 months, respectively.² Placing sutures superficially in the dermis has been found to increase the rate of spitting.⁵ Throwing more knots per closure also has been found to increase the rate of spitting.⁵

How to Decrease Spitting
Careful choice of suture material and proper depth of suture placement might decrease the risk for spitting in dermatologic surgery. Furthermore, if polyglactin 910 or a long-lasting suture is to be used, sutures should be placed deeply.

What to Do If Sutures Spit
When a suture has begun to spit, the extruding foreign material needs to be removed and the surgical site assessed for infection or abscess. Exposed suture material typically can be removed with forceps without local anesthesia. In some cases, fine-tipped Bishop-Harmon tissue forceps or jewelers forceps might be required.

If the suture cannot be removed completely, it should be trimmed as short as possible. This can be accomplished by pulling on the exposed end of the suture, tenting the skin, and trimming it as close as possible to the surface. Once the foreign material is removed, assessment for signs of infection is paramount.

How to Manage Infection—Postoperative infection associated with a spitting suture can take the form of a periwound cellulitis or stitch abscess.³ A stitch abscess can reflect a sterile inflammatory response to the buried suture or a true infection⁴; the former is more common.³ In the event of an infected stitch abscess, provide warm compresses, obtain specimens for culture, and prescribe antibiotics after the spitting suture has been removed. Incision and drainage also might be required if notable fluctuance is present.

It is crucial for dermatologic surgeons to identify and manage these complications. Figure 2 illustrates an algorithmic approach to managing spitting sutures.

Practical Implications

Spitting sutures are a common occurrence following dermatologic surgery that can lead to remarkable patient distress. Fortunately, in the absence of superimposed infection, spitting sutures have not been shown to worsen outcomes of healing and scarring.⁵ Nevertheless, it is important to identify and appropriately treat this common complication. The simple algorithm we provide (Figure 2) aids in cutaneous surgery by providing a straightforward approach to managing spitting sutures and their complications.

Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

A range of dermatologic manifestations of COVID-19 have been reported, including nonspecific maculopapular exanthems, urticaria, and varicellalike eruptions.¹ Additionally, there have been sporadic accounts of cutaneous vasculopathic signs such as perniolike lesions, acro-ischemia, livedo reticularis, and retiform purpura.² We describe exuberant hemorrhagic bullae occurring on the extremities of 2 critically ill patients with COVID-19. We hypothesized that the bullae were vasculopathic in nature and possibly exacerbated by peripheral intravenous (IV)–related injury.

A 62-year-old woman with a history of diabetes mellitus and chronic obstructive pulmonary disease was admitted to the intensive care unit for acute hypoxemic respiratory failure secondary to COVID-19 infection. Dermatology was consulted for evaluation of blisters on the right arm. A new peripheral IV line was inserted into the patient’s right forearm for treatment of secondary methicillin-resistant Staphylococcus aureus pneumonia. The peripheral IV was inserted into the right proximal forearm for 2 days prior to development of ecchymosis and blisters. Intravenous medications included vancomycin, cefepime, methylprednisolone, and famotidine, as well as maintenance fluids (normal saline). Physical examination revealed extensive confluent ecchymoses with overlying tense bullae (Figure 1). Notable laboratory findings included an elevated D-dimer (peak of 8.67 μg/mL fibrinogen-equivalent units [FEUs], reference range <0.5 μg/mL FEU) and fibrinogen (789 mg/dL, reference range 200–400 mg/dL) levels. Three days later she developed worsening edema of the right arm, accompanied by more extensive bullae formation (Figure 2). Computed tomography of the right arm showed extensive subcutaneous stranding and subcutaneous edema. An orthopedic consultation determined that there was no compartment syndrome, and surgical intervention was not recommended. The patient’s course was complicated by multiorgan failure, and she died 18 days after admission.

Extravasation injury results from unintentional administration of potentially vesicant substances into tissues surrounding the intended vascular channel.⁴ The mechanism of action of these injuries is postulated to arise from direct tissue injury from cytotoxic substances, elevated osmotic pressure, and reduced blood supply if vasoconstrictive substances are infused.⁵ In our patients, these injuries also may have promoted vascular occlusion leading to the brisk reaction observed. Although ecchymoses typically are associated with hypocoagulable states, both of our patients were noted to have normal platelet levels throughout hospitalization. Additionally, findings of elevated D-dimer and fibrinogen levels point to a hypercoagulable state. However, there is a possibility of platelet dysfunction leading to the observed cutaneous findings of ecchymoses. Thrombocytopenia is a common finding in patients with COVID-19 and is found to be associated with increased in-hospital mortality.⁶ Additional study of these reactions is needed given the propensity for multiorgan failure and death in patients with COVID-19 from suspected diffuse microvascular damage.³

To the Editor:

A range of dermatologic manifestations of COVID-19 have been reported, including nonspecific maculopapular exanthems, urticaria, and varicellalike eruptions.¹ Additionally, there have been sporadic accounts of cutaneous vasculopathic signs such as perniolike lesions, acro-ischemia, livedo reticularis, and retiform purpura.² We describe exuberant hemorrhagic bullae occurring on the extremities of 2 critically ill patients with COVID-19. We hypothesized that the bullae were vasculopathic in nature and possibly exacerbated by peripheral intravenous (IV)–related injury.

A 62-year-old woman with a history of diabetes mellitus and chronic obstructive pulmonary disease was admitted to the intensive care unit for acute hypoxemic respiratory failure secondary to COVID-19 infection. Dermatology was consulted for evaluation of blisters on the right arm. A new peripheral IV line was inserted into the patient’s right forearm for treatment of secondary methicillin-resistant Staphylococcus aureus pneumonia. The peripheral IV was inserted into the right proximal forearm for 2 days prior to development of ecchymosis and blisters. Intravenous medications included vancomycin, cefepime, methylprednisolone, and famotidine, as well as maintenance fluids (normal saline). Physical examination revealed extensive confluent ecchymoses with overlying tense bullae (Figure 1). Notable laboratory findings included an elevated D-dimer (peak of 8.67 μg/mL fibrinogen-equivalent units [FEUs], reference range <0.5 μg/mL FEU) and fibrinogen (789 mg/dL, reference range 200–400 mg/dL) levels. Three days later she developed worsening edema of the right arm, accompanied by more extensive bullae formation (Figure 2). Computed tomography of the right arm showed extensive subcutaneous stranding and subcutaneous edema. An orthopedic consultation determined that there was no compartment syndrome, and surgical intervention was not recommended. The patient’s course was complicated by multiorgan failure, and she died 18 days after admission.

Extravasation injury results from unintentional administration of potentially vesicant substances into tissues surrounding the intended vascular channel.⁴ The mechanism of action of these injuries is postulated to arise from direct tissue injury from cytotoxic substances, elevated osmotic pressure, and reduced blood supply if vasoconstrictive substances are infused.⁵ In our patients, these injuries also may have promoted vascular occlusion leading to the brisk reaction observed. Although ecchymoses typically are associated with hypocoagulable states, both of our patients were noted to have normal platelet levels throughout hospitalization. Additionally, findings of elevated D-dimer and fibrinogen levels point to a hypercoagulable state. However, there is a possibility of platelet dysfunction leading to the observed cutaneous findings of ecchymoses. Thrombocytopenia is a common finding in patients with COVID-19 and is found to be associated with increased in-hospital mortality.⁶ Additional study of these reactions is needed given the propensity for multiorgan failure and death in patients with COVID-19 from suspected diffuse microvascular damage.³

To the Editor:

A range of dermatologic manifestations of COVID-19 have been reported, including nonspecific maculopapular exanthems, urticaria, and varicellalike eruptions.¹ Additionally, there have been sporadic accounts of cutaneous vasculopathic signs such as perniolike lesions, acro-ischemia, livedo reticularis, and retiform purpura.² We describe exuberant hemorrhagic bullae occurring on the extremities of 2 critically ill patients with COVID-19. We hypothesized that the bullae were vasculopathic in nature and possibly exacerbated by peripheral intravenous (IV)–related injury.

A 62-year-old woman with a history of diabetes mellitus and chronic obstructive pulmonary disease was admitted to the intensive care unit for acute hypoxemic respiratory failure secondary to COVID-19 infection. Dermatology was consulted for evaluation of blisters on the right arm. A new peripheral IV line was inserted into the patient’s right forearm for treatment of secondary methicillin-resistant Staphylococcus aureus pneumonia. The peripheral IV was inserted into the right proximal forearm for 2 days prior to development of ecchymosis and blisters. Intravenous medications included vancomycin, cefepime, methylprednisolone, and famotidine, as well as maintenance fluids (normal saline). Physical examination revealed extensive confluent ecchymoses with overlying tense bullae (Figure 1). Notable laboratory findings included an elevated D-dimer (peak of 8.67 μg/mL fibrinogen-equivalent units [FEUs], reference range <0.5 μg/mL FEU) and fibrinogen (789 mg/dL, reference range 200–400 mg/dL) levels. Three days later she developed worsening edema of the right arm, accompanied by more extensive bullae formation (Figure 2). Computed tomography of the right arm showed extensive subcutaneous stranding and subcutaneous edema. An orthopedic consultation determined that there was no compartment syndrome, and surgical intervention was not recommended. The patient’s course was complicated by multiorgan failure, and she died 18 days after admission.

Extravasation injury results from unintentional administration of potentially vesicant substances into tissues surrounding the intended vascular channel.⁴ The mechanism of action of these injuries is postulated to arise from direct tissue injury from cytotoxic substances, elevated osmotic pressure, and reduced blood supply if vasoconstrictive substances are infused.⁵ In our patients, these injuries also may have promoted vascular occlusion leading to the brisk reaction observed. Although ecchymoses typically are associated with hypocoagulable states, both of our patients were noted to have normal platelet levels throughout hospitalization. Additionally, findings of elevated D-dimer and fibrinogen levels point to a hypercoagulable state. However, there is a possibility of platelet dysfunction leading to the observed cutaneous findings of ecchymoses. Thrombocytopenia is a common finding in patients with COVID-19 and is found to be associated with increased in-hospital mortality.⁶ Additional study of these reactions is needed given the propensity for multiorgan failure and death in patients with COVID-19 from suspected diffuse microvascular damage.³

The Diagnosis: Tinea Pseudoimbricata

Tinea pseudoimbricata and tinea indecisiva are synonyms describing cases of tinea corporis that manifest in scaly plaques in concentric rings evocative of those present in tinea imbricata. However, in contrast to tinea imbricata, cases of tinea pseudoimbricata are caused by dermatophytes other than Trichophyton concentricum. ¹ Tinea pseudoimbricata usually presents in association with immunosuppression, either systemic or local, and can be produced by application of topical medications such as corticosteroids.² Mask-Bull et al³ reported the case of a 21-year-old man in the United States with no history of immunosuppressive conditions who presented with scaly erythematous annular plaques on the lateral neck that resolved with 2 pulsed doses of terbinafine. Potassium hydroxide preparation and fungal culture were both consistent with Trichophyton tonsurans.³

Trichophyton concentricum is an anthropophilic species of dermatophyte endemic to areas within the South Pacific, Southeast Asia, and Central and South America. Infection with T concentricum produces tinea imbricata, which presents with concentric, scaly, annular rings. Cutaneous lesions of tinea imbricata caused by T concentricum have a more generalized distribution and more densely grouped, concentric circles than the cutaneous findings seen in patients with tinea pseudoimbricata.⁴ Affected patients typically demonstrate negative delayed-type hypersensitivity to T concentricum cytoplasmic antigen and T-lymphocyte hyporeactivity, which may contribute to the development of sequential waves of scaling observed in tinea imbricata.⁵

Trichophyton rubrum, the most common cause of tinea corporis, has been reported to cause some cases of tinea pseudoimbricata (indecisiva).^1,2 It utilizes keratinases such as subtilisins (Sub3 and Sub4), leucine aminopeptidases (Lap1 and Lap2), and dipeptidyl peptidases (DppIV and DppV) to invade the skin. Once inside, mannans, glycoprotein constituents of the cell wall, are released and bind to the cell surface of mononuclear phagocytes, subsequently moving into the cell by phagocytosis, thereafter interfering with RNA synthesis that is necessary for presentation of antigens to appropriate T cells and allowing for initiation of chronic infection.^6,7 The cytotoxic response to superficial dermatophyte infection is triggered by major histocompatibility complex class I molecule activation of CD8⁺ cells.^6,8

Our case is of interest given the localization of the superficial dermatophyte infection to only vitiliginous skin. This distribution and appearance while undergoing narrowband UVB (NB-UVB) treatment is rare. We postulate that our patient likely represents a case of locus minoris resistentiae, a phenomenon in which an area of skin exhibits a compromised immune microenvironment that predisposes it to disease.⁹

In vitiligo, NB-UVB modulates the immune response by increasing IL-10, thereby promoting regulatory T-cell differentiation with suppression of autoreactive T cells and induction of direct T-lymphocyte apoptosis.^10,11 Although the mechanism accounting for our patient’s presentation is unknown, we suspect NB-UVB–induced immunosuppression enabled persistence of the dermatophyte infection. The localization of the infection to the vitiliginous patches may result from the greater penetration of the UV light relative to the surrounding, normally pigmented skin. This relative difference in UV penetration would be expected to result in increased immunosuppression in the vitiliginous lesions and enhanced susceptibility to the fungal organisms.

Erythema annulare centrifugum is characterized by annular lesions with a trailing scale instead of the concentric rings seen in tinea pseudoimbricata. Erythema marginatum is seen in acute rheumatic fever and presents with a transient nonpruritic rash, usually on the trunk or extremities. Erythema migrans presents with fewer lesions that are less circinate in shape, and the patient often has a history of a tick bite. Tinea imbricata is caused by T concentricum, while tinea pseudoimbricata is caused by T tonsurans and other dermatophytes.

With the increasing use of immunosuppressant drugs, the prevalence of tinea pseudoimbricata is hypothesized to increase.¹ The presence of tinea pseudoimbricata should alert dermatologists to the possible overuse of topical corticosteroids, and other forms of immunosuppression also should be considered.

The Diagnosis: Tinea Pseudoimbricata

Tinea pseudoimbricata and tinea indecisiva are synonyms describing cases of tinea corporis that manifest in scaly plaques in concentric rings evocative of those present in tinea imbricata. However, in contrast to tinea imbricata, cases of tinea pseudoimbricata are caused by dermatophytes other than Trichophyton concentricum. ¹ Tinea pseudoimbricata usually presents in association with immunosuppression, either systemic or local, and can be produced by application of topical medications such as corticosteroids.² Mask-Bull et al³ reported the case of a 21-year-old man in the United States with no history of immunosuppressive conditions who presented with scaly erythematous annular plaques on the lateral neck that resolved with 2 pulsed doses of terbinafine. Potassium hydroxide preparation and fungal culture were both consistent with Trichophyton tonsurans.³

Trichophyton concentricum is an anthropophilic species of dermatophyte endemic to areas within the South Pacific, Southeast Asia, and Central and South America. Infection with T concentricum produces tinea imbricata, which presents with concentric, scaly, annular rings. Cutaneous lesions of tinea imbricata caused by T concentricum have a more generalized distribution and more densely grouped, concentric circles than the cutaneous findings seen in patients with tinea pseudoimbricata.⁴ Affected patients typically demonstrate negative delayed-type hypersensitivity to T concentricum cytoplasmic antigen and T-lymphocyte hyporeactivity, which may contribute to the development of sequential waves of scaling observed in tinea imbricata.⁵

Trichophyton rubrum, the most common cause of tinea corporis, has been reported to cause some cases of tinea pseudoimbricata (indecisiva).^1,2 It utilizes keratinases such as subtilisins (Sub3 and Sub4), leucine aminopeptidases (Lap1 and Lap2), and dipeptidyl peptidases (DppIV and DppV) to invade the skin. Once inside, mannans, glycoprotein constituents of the cell wall, are released and bind to the cell surface of mononuclear phagocytes, subsequently moving into the cell by phagocytosis, thereafter interfering with RNA synthesis that is necessary for presentation of antigens to appropriate T cells and allowing for initiation of chronic infection.^6,7 The cytotoxic response to superficial dermatophyte infection is triggered by major histocompatibility complex class I molecule activation of CD8⁺ cells.^6,8

Our case is of interest given the localization of the superficial dermatophyte infection to only vitiliginous skin. This distribution and appearance while undergoing narrowband UVB (NB-UVB) treatment is rare. We postulate that our patient likely represents a case of locus minoris resistentiae, a phenomenon in which an area of skin exhibits a compromised immune microenvironment that predisposes it to disease.⁹

In vitiligo, NB-UVB modulates the immune response by increasing IL-10, thereby promoting regulatory T-cell differentiation with suppression of autoreactive T cells and induction of direct T-lymphocyte apoptosis.^10,11 Although the mechanism accounting for our patient’s presentation is unknown, we suspect NB-UVB–induced immunosuppression enabled persistence of the dermatophyte infection. The localization of the infection to the vitiliginous patches may result from the greater penetration of the UV light relative to the surrounding, normally pigmented skin. This relative difference in UV penetration would be expected to result in increased immunosuppression in the vitiliginous lesions and enhanced susceptibility to the fungal organisms.

Erythema annulare centrifugum is characterized by annular lesions with a trailing scale instead of the concentric rings seen in tinea pseudoimbricata. Erythema marginatum is seen in acute rheumatic fever and presents with a transient nonpruritic rash, usually on the trunk or extremities. Erythema migrans presents with fewer lesions that are less circinate in shape, and the patient often has a history of a tick bite. Tinea imbricata is caused by T concentricum, while tinea pseudoimbricata is caused by T tonsurans and other dermatophytes.

With the increasing use of immunosuppressant drugs, the prevalence of tinea pseudoimbricata is hypothesized to increase.¹ The presence of tinea pseudoimbricata should alert dermatologists to the possible overuse of topical corticosteroids, and other forms of immunosuppression also should be considered.

The Diagnosis: Tinea Pseudoimbricata

Tinea pseudoimbricata and tinea indecisiva are synonyms describing cases of tinea corporis that manifest in scaly plaques in concentric rings evocative of those present in tinea imbricata. However, in contrast to tinea imbricata, cases of tinea pseudoimbricata are caused by dermatophytes other than Trichophyton concentricum. ¹ Tinea pseudoimbricata usually presents in association with immunosuppression, either systemic or local, and can be produced by application of topical medications such as corticosteroids.² Mask-Bull et al³ reported the case of a 21-year-old man in the United States with no history of immunosuppressive conditions who presented with scaly erythematous annular plaques on the lateral neck that resolved with 2 pulsed doses of terbinafine. Potassium hydroxide preparation and fungal culture were both consistent with Trichophyton tonsurans.³

Trichophyton concentricum is an anthropophilic species of dermatophyte endemic to areas within the South Pacific, Southeast Asia, and Central and South America. Infection with T concentricum produces tinea imbricata, which presents with concentric, scaly, annular rings. Cutaneous lesions of tinea imbricata caused by T concentricum have a more generalized distribution and more densely grouped, concentric circles than the cutaneous findings seen in patients with tinea pseudoimbricata.⁴ Affected patients typically demonstrate negative delayed-type hypersensitivity to T concentricum cytoplasmic antigen and T-lymphocyte hyporeactivity, which may contribute to the development of sequential waves of scaling observed in tinea imbricata.⁵

Trichophyton rubrum, the most common cause of tinea corporis, has been reported to cause some cases of tinea pseudoimbricata (indecisiva).^1,2 It utilizes keratinases such as subtilisins (Sub3 and Sub4), leucine aminopeptidases (Lap1 and Lap2), and dipeptidyl peptidases (DppIV and DppV) to invade the skin. Once inside, mannans, glycoprotein constituents of the cell wall, are released and bind to the cell surface of mononuclear phagocytes, subsequently moving into the cell by phagocytosis, thereafter interfering with RNA synthesis that is necessary for presentation of antigens to appropriate T cells and allowing for initiation of chronic infection.^6,7 The cytotoxic response to superficial dermatophyte infection is triggered by major histocompatibility complex class I molecule activation of CD8⁺ cells.^6,8

Our case is of interest given the localization of the superficial dermatophyte infection to only vitiliginous skin. This distribution and appearance while undergoing narrowband UVB (NB-UVB) treatment is rare. We postulate that our patient likely represents a case of locus minoris resistentiae, a phenomenon in which an area of skin exhibits a compromised immune microenvironment that predisposes it to disease.⁹

In vitiligo, NB-UVB modulates the immune response by increasing IL-10, thereby promoting regulatory T-cell differentiation with suppression of autoreactive T cells and induction of direct T-lymphocyte apoptosis.^10,11 Although the mechanism accounting for our patient’s presentation is unknown, we suspect NB-UVB–induced immunosuppression enabled persistence of the dermatophyte infection. The localization of the infection to the vitiliginous patches may result from the greater penetration of the UV light relative to the surrounding, normally pigmented skin. This relative difference in UV penetration would be expected to result in increased immunosuppression in the vitiliginous lesions and enhanced susceptibility to the fungal organisms.

Erythema annulare centrifugum is characterized by annular lesions with a trailing scale instead of the concentric rings seen in tinea pseudoimbricata. Erythema marginatum is seen in acute rheumatic fever and presents with a transient nonpruritic rash, usually on the trunk or extremities. Erythema migrans presents with fewer lesions that are less circinate in shape, and the patient often has a history of a tick bite. Tinea imbricata is caused by T concentricum, while tinea pseudoimbricata is caused by T tonsurans and other dermatophytes.

With the increasing use of immunosuppressant drugs, the prevalence of tinea pseudoimbricata is hypothesized to increase.¹ The presence of tinea pseudoimbricata should alert dermatologists to the possible overuse of topical corticosteroids, and other forms of immunosuppression also should be considered.

To the Editor:

A 62-year-old woman with a history of dermatomyositis (DM) presented to dermatology clinic for evaluation of multiple subcutaneous nodules. Two years prior to the current presentation, the patient was diagnosed by her primary care physician with DM based on clinical presentation. She initially developed body aches, muscle pain, and weakness of the upper extremities, specifically around the shoulders, and later the lower extremities, specifically around the thighs. The initial physical examination revealed pain with movement, tenderness to palpation, and proximal extremity weakness. The patient also noted a 50-lb weight loss. Over the next year, she noted dysphagia and developed multiple subcutaneous nodules on the right arm, chest, and left axilla. Subsequently, she developed a violaceous, hyperpigmented, periorbital rash and erythema of the anterior chest. She did not experience hair loss, oral ulcers, photosensitivity, or joint pain.

Laboratory testing in the months following the initial presentation revealed a creatine phosphokinase level of 436 U/L (reference range, 20–200 U/L), an erythrocyte sedimentation rate of 60 mm/h (reference range, <31 mm/h), and an aldolase level of 10.4 U/L (reference range, 1.0–8.0 U/L). Lactate dehydrogenase and thyroid function tests were within normal limits. Antinuclear antibodies, anti–double-stranded DNA, anti-Smith antibodies, anti-ribonucleoprotein, anti–Jo-1 antibodies, and anti–smooth muscle antibodies all were negative. Total blood complement levels were elevated, but complement C3 and C4 were within normal limits. Imaging demonstrated normal chest radiographs, and a modified barium swallow confirmed swallowing dysfunction. A right quadricep muscle biopsy confirmed the diagnosis of DM. A malignancy work-up including mammography, colonoscopy, and computed tomography of the chest, abdomen, and pelvis was negative aside from nodular opacities in the chest. She was treated with prednisone (60 mg, 0.9 mg/kg) daily and methotrexate (15–20 mg) weekly for several months. While the treatment attenuated the rash and improved weakness, the nodules persisted, prompting a referral to dermatology.

Physical examination at the dermatology clinic demonstrated the persistent subcutaneous nodules were indurated and bilaterally located on the arms, axillae, chest, abdomen, buttocks, and thighs with no pain or erythema (Figure). Laboratory tests demonstrated a normal creatine phosphokinase level, elevated erythrocyte sedimentation rate (70 mm/h), and elevated aldolase level (9.3 U/L). Complement levels were elevated, though complement C3 and C4 remained within normal limits. Histopathology of nodules from the medial right upper arm and left thigh showed lobular panniculitis with fat necrosis, calcification, and interface changes. The patient was treated for several months with daily mycophenolate mofetil (1 g increased to 3 g) and daily hydroxychloroquine (200 mg) without any effect on the nodules.

A majority of the reported panniculitis cases in DM have responded to treatment with prednisone; however, treatment with prednisone has been more recalcitrant in other cases. Reports of successful additional therapies include methotrexate, cyclosporine, azathioprine, hydroxychloroquine, intravenous immunoglobulin, mepacrine, or a combination of these entities.^19,22 In most cases, improvement of the panniculitis and other DM symptoms occurred simultaneously.²⁵ It is noteworthy that the muscular symptoms often resolved more rapidly than cutaneous manifestations.³³ Few reported cases (6 including the current case) found a persistent panniculitis despite improvement and remission of the myositis.^3,5,10,11,30

Our patient was treated with both prednisone and methotrexate for several months, leading to remission of muscular symptoms (along with return to baseline of creatine phosphokinase), yet the panniculitis did not improve. The subcutaneous nodules also did not respond to treatment with mycophenolate mofetil and hydroxychloroquine.

Recent immunohistochemical studies have suggested that panniculitic lesions show better outcomes with immunosuppressive therapy when compared with other DM-related skin lesions.⁴⁰ However, this was not the case for our patient, who after months of immunosuppressive therapy showed complete resolution of the periorbital and chest rashes with persistence of multiple indurated subcutaneous nodules.

Our case adds to a number of reports of DM presenting with panniculitis. Our patient fit the classic demographic of previously reported cases, as she was an adult woman without evidence of underlying malignancy; however, our case remains an example of the therapeutic challenge that exists when encountering a persistent, treatment-resistant panniculitis despite resolution of all other features of DM.

TABLE IS AVAILABLE IN THE PDF OF THIS ARTICLE

To the Editor:

A 62-year-old woman with a history of dermatomyositis (DM) presented to dermatology clinic for evaluation of multiple subcutaneous nodules. Two years prior to the current presentation, the patient was diagnosed by her primary care physician with DM based on clinical presentation. She initially developed body aches, muscle pain, and weakness of the upper extremities, specifically around the shoulders, and later the lower extremities, specifically around the thighs. The initial physical examination revealed pain with movement, tenderness to palpation, and proximal extremity weakness. The patient also noted a 50-lb weight loss. Over the next year, she noted dysphagia and developed multiple subcutaneous nodules on the right arm, chest, and left axilla. Subsequently, she developed a violaceous, hyperpigmented, periorbital rash and erythema of the anterior chest. She did not experience hair loss, oral ulcers, photosensitivity, or joint pain.

Laboratory testing in the months following the initial presentation revealed a creatine phosphokinase level of 436 U/L (reference range, 20–200 U/L), an erythrocyte sedimentation rate of 60 mm/h (reference range, <31 mm/h), and an aldolase level of 10.4 U/L (reference range, 1.0–8.0 U/L). Lactate dehydrogenase and thyroid function tests were within normal limits. Antinuclear antibodies, anti–double-stranded DNA, anti-Smith antibodies, anti-ribonucleoprotein, anti–Jo-1 antibodies, and anti–smooth muscle antibodies all were negative. Total blood complement levels were elevated, but complement C3 and C4 were within normal limits. Imaging demonstrated normal chest radiographs, and a modified barium swallow confirmed swallowing dysfunction. A right quadricep muscle biopsy confirmed the diagnosis of DM. A malignancy work-up including mammography, colonoscopy, and computed tomography of the chest, abdomen, and pelvis was negative aside from nodular opacities in the chest. She was treated with prednisone (60 mg, 0.9 mg/kg) daily and methotrexate (15–20 mg) weekly for several months. While the treatment attenuated the rash and improved weakness, the nodules persisted, prompting a referral to dermatology.

Physical examination at the dermatology clinic demonstrated the persistent subcutaneous nodules were indurated and bilaterally located on the arms, axillae, chest, abdomen, buttocks, and thighs with no pain or erythema (Figure). Laboratory tests demonstrated a normal creatine phosphokinase level, elevated erythrocyte sedimentation rate (70 mm/h), and elevated aldolase level (9.3 U/L). Complement levels were elevated, though complement C3 and C4 remained within normal limits. Histopathology of nodules from the medial right upper arm and left thigh showed lobular panniculitis with fat necrosis, calcification, and interface changes. The patient was treated for several months with daily mycophenolate mofetil (1 g increased to 3 g) and daily hydroxychloroquine (200 mg) without any effect on the nodules.

A majority of the reported panniculitis cases in DM have responded to treatment with prednisone; however, treatment with prednisone has been more recalcitrant in other cases. Reports of successful additional therapies include methotrexate, cyclosporine, azathioprine, hydroxychloroquine, intravenous immunoglobulin, mepacrine, or a combination of these entities.^19,22 In most cases, improvement of the panniculitis and other DM symptoms occurred simultaneously.²⁵ It is noteworthy that the muscular symptoms often resolved more rapidly than cutaneous manifestations.³³ Few reported cases (6 including the current case) found a persistent panniculitis despite improvement and remission of the myositis.^3,5,10,11,30

Our patient was treated with both prednisone and methotrexate for several months, leading to remission of muscular symptoms (along with return to baseline of creatine phosphokinase), yet the panniculitis did not improve. The subcutaneous nodules also did not respond to treatment with mycophenolate mofetil and hydroxychloroquine.

Recent immunohistochemical studies have suggested that panniculitic lesions show better outcomes with immunosuppressive therapy when compared with other DM-related skin lesions.⁴⁰ However, this was not the case for our patient, who after months of immunosuppressive therapy showed complete resolution of the periorbital and chest rashes with persistence of multiple indurated subcutaneous nodules.

Our case adds to a number of reports of DM presenting with panniculitis. Our patient fit the classic demographic of previously reported cases, as she was an adult woman without evidence of underlying malignancy; however, our case remains an example of the therapeutic challenge that exists when encountering a persistent, treatment-resistant panniculitis despite resolution of all other features of DM.

TABLE IS AVAILABLE IN THE PDF OF THIS ARTICLE

To the Editor:

A 62-year-old woman with a history of dermatomyositis (DM) presented to dermatology clinic for evaluation of multiple subcutaneous nodules. Two years prior to the current presentation, the patient was diagnosed by her primary care physician with DM based on clinical presentation. She initially developed body aches, muscle pain, and weakness of the upper extremities, specifically around the shoulders, and later the lower extremities, specifically around the thighs. The initial physical examination revealed pain with movement, tenderness to palpation, and proximal extremity weakness. The patient also noted a 50-lb weight loss. Over the next year, she noted dysphagia and developed multiple subcutaneous nodules on the right arm, chest, and left axilla. Subsequently, she developed a violaceous, hyperpigmented, periorbital rash and erythema of the anterior chest. She did not experience hair loss, oral ulcers, photosensitivity, or joint pain.

Laboratory testing in the months following the initial presentation revealed a creatine phosphokinase level of 436 U/L (reference range, 20–200 U/L), an erythrocyte sedimentation rate of 60 mm/h (reference range, <31 mm/h), and an aldolase level of 10.4 U/L (reference range, 1.0–8.0 U/L). Lactate dehydrogenase and thyroid function tests were within normal limits. Antinuclear antibodies, anti–double-stranded DNA, anti-Smith antibodies, anti-ribonucleoprotein, anti–Jo-1 antibodies, and anti–smooth muscle antibodies all were negative. Total blood complement levels were elevated, but complement C3 and C4 were within normal limits. Imaging demonstrated normal chest radiographs, and a modified barium swallow confirmed swallowing dysfunction. A right quadricep muscle biopsy confirmed the diagnosis of DM. A malignancy work-up including mammography, colonoscopy, and computed tomography of the chest, abdomen, and pelvis was negative aside from nodular opacities in the chest. She was treated with prednisone (60 mg, 0.9 mg/kg) daily and methotrexate (15–20 mg) weekly for several months. While the treatment attenuated the rash and improved weakness, the nodules persisted, prompting a referral to dermatology.

Physical examination at the dermatology clinic demonstrated the persistent subcutaneous nodules were indurated and bilaterally located on the arms, axillae, chest, abdomen, buttocks, and thighs with no pain or erythema (Figure). Laboratory tests demonstrated a normal creatine phosphokinase level, elevated erythrocyte sedimentation rate (70 mm/h), and elevated aldolase level (9.3 U/L). Complement levels were elevated, though complement C3 and C4 remained within normal limits. Histopathology of nodules from the medial right upper arm and left thigh showed lobular panniculitis with fat necrosis, calcification, and interface changes. The patient was treated for several months with daily mycophenolate mofetil (1 g increased to 3 g) and daily hydroxychloroquine (200 mg) without any effect on the nodules.

A majority of the reported panniculitis cases in DM have responded to treatment with prednisone; however, treatment with prednisone has been more recalcitrant in other cases. Reports of successful additional therapies include methotrexate, cyclosporine, azathioprine, hydroxychloroquine, intravenous immunoglobulin, mepacrine, or a combination of these entities.^19,22 In most cases, improvement of the panniculitis and other DM symptoms occurred simultaneously.²⁵ It is noteworthy that the muscular symptoms often resolved more rapidly than cutaneous manifestations.³³ Few reported cases (6 including the current case) found a persistent panniculitis despite improvement and remission of the myositis.^3,5,10,11,30

Our patient was treated with both prednisone and methotrexate for several months, leading to remission of muscular symptoms (along with return to baseline of creatine phosphokinase), yet the panniculitis did not improve. The subcutaneous nodules also did not respond to treatment with mycophenolate mofetil and hydroxychloroquine.

Recent immunohistochemical studies have suggested that panniculitic lesions show better outcomes with immunosuppressive therapy when compared with other DM-related skin lesions.⁴⁰ However, this was not the case for our patient, who after months of immunosuppressive therapy showed complete resolution of the periorbital and chest rashes with persistence of multiple indurated subcutaneous nodules.

Our case adds to a number of reports of DM presenting with panniculitis. Our patient fit the classic demographic of previously reported cases, as she was an adult woman without evidence of underlying malignancy; however, our case remains an example of the therapeutic challenge that exists when encountering a persistent, treatment-resistant panniculitis despite resolution of all other features of DM.

TABLE IS AVAILABLE IN THE PDF OF THIS ARTICLE

The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

The Diagnosis: Hidradenocarcinoma

An excisional biopsy revealed a neoplasm in the dermis with focal invasion into the adjacent soft tissue (Figure 1). The tumor consisted of sheets of cells with cytoplasmic vacuoles and ductal differentiation (Figure 2), as well as cells with mild atypia, mild pleomorphism, rare mitotic figures, and abundant pale cytoplasm. Immunohistochemical staining was positive for cytokeratin (CK) 5, CK7, CK20, CK AE1/AE3, and p63 (Figure 3). The culmination of features including the large tumor size, immunohistochemical staining pattern, and mild pleomorphism with focal invasion into the soft tissue supported the diagnosis of hidradenocarcinoma.

Hidradenocarcinoma is an exceedingly rare malignant tumor of eccrine and/or apocrine origin.¹ It accounts for less than 0.001% of all tumors and 1 of 13,000 skin biopsies.² It usually arises in the head and neck region and most commonly affects older adults aged 50 to 70 years.³ The size of hidradenocarcinomas can vary; however, they typically are large, often growing to be greater than 5 cm in diameter.² It tends to be an aggressive tumor that generally spreads to regional lymph nodes and distant viscera.⁴ Although it most commonly arises de novo, it may occasionally derive from a benign hidradenoma.¹ The diagnosis of hidradenocarcinoma is made based on the tumor’s morphologic and pathologic characteristics. Histologically, it is characterized by an infiltrative and invasive proliferation of lobules made of large clear cells with atypical mitotic figures and nuclear pleomorphism as well as immunohistochemical features displaying various positive markers, such as carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, and CKs AE1/AE3 and 5/6.² Invasion of the adjacent soft tissue can be present and helps to confirm the diagnosis.

The differential diagnosis for hidradenocarcinoma primarily is the benign hidradenoma, which is similar both clinically and histologically with a few important differences. Hidradenocarcinomas often are larger and ulcerated. Histologically, they usually are more pleomorphic with the presence of mitotic figures in clear cells and tend to invade locally into the surrounding soft tissue. Other similar lesions such as spiradenoma, Merkel cell carcinoma, lymphangioma, cutaneous Crohn disease, tumors metastatic to the skin, and metastatic clear cell carcinomas originating from other organs also are included in the differential diagnosis.²

Spiradenomas are dermal tumors originating from the sweat glands. They typically present as bluish, painful, solitary nodules on the ventral surfaces of the upper body, though multiple nodules also are reported.⁵ Spiradenomas manifest as a central constellation of pale large cells surrounded by small, dark, basaloid cells containing hyperchromatic nuclei. The microscopic appearance of the blue basaloid cells contrasts with the clear cells seen in hidradenoma.⁵

Merkel cell carcinoma is a cutaneous neuroendocrine tumor affecting elderly or immunosuppressed individuals. It arises in sun-exposed areas and often is associated with Merkel cell polyomavirus infection. The histologic features display small and round cells that stain positive for CK8, CK18, CK19, and CK20 but stain negative for CK7, a marker that often is positive in hidradenocarcinoma.⁶

Lymphangioma, particularly cavernous lymphangioma, may resemble the gross appearance of hidradenoma/ hidradenocarcinoma. It usually presents as irregular clear blue papules and nodules in the skin and subcutaneous tissue.⁷ The key histopathologic finding in this tumor is the endothelium-lined channels that stain positive for D2-40, a lymphatic endothelium marker.^7,8

Cutaneous Crohn disease is classified as noncaseating granulomatous skin lesions that are noncontinuous with the gastrointestinal tract.⁹ Clinical presentations in addition to skin edema include erythematous plaques, ulcerations, and erosions. Histopathology reveals sterile noncaseating granulomas made of Langerhans giant cells, epithelioid histocytes, and plasma cells.⁹

Metastatic clear cell carcinomas, such as renal cell carcinoma, can be differentiated by a history of primary carcinoma, demonstration of histologic vascular stroma, and other features related to metastatic clear cell carcinoma.²

There are no well-established therapeutic guidelines for hidradenocarcinoma. Wide local excision with margins greater than 2 cm is the preferred initial treatment and often is performed in conjunction with sentinel lymph node biopsy. External beam radiotherapy and adjunctive chemotherapy have been used for tumors that could not be surgically cleared. However, the efficacy of these treatments has not been well established.² Targeted therapies recently have emerged as an alternative treatment choice for hidradenocarcinoma due to the utilization of immunohistochemical and genomic testing. The discovery of specific gene mutations or the expression of hormonal receptors in this tumor have paved the way for targeting HER2-expressing hidradenocarcinomas with trastuzumab and those expressing estrogen receptor with the estrogen receptor inhibitor tamoxifen.¹ Epidermal growth factor receptor inhibitors and PI3K/Akt/mTOR (phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin) pathway inhibitors also have been used to target various signal transduction pathways.²

Wide excision with 2.5-cm margins was performed on our patient, and a positron emission tomography– computed tomography scan revealed no metastatic disease. She declined sentinel lymph node biopsy and additional treatment. Due to the risk for recurrence, she was monitored closely with skin examinations and positron emission tomography–computed tomography every 3 months for the first year and every 6 months thereafter. Thus far, she has had no evidence of local or regional recurrence.

The Diagnosis: Hidradenocarcinoma

An excisional biopsy revealed a neoplasm in the dermis with focal invasion into the adjacent soft tissue (Figure 1). The tumor consisted of sheets of cells with cytoplasmic vacuoles and ductal differentiation (Figure 2), as well as cells with mild atypia, mild pleomorphism, rare mitotic figures, and abundant pale cytoplasm. Immunohistochemical staining was positive for cytokeratin (CK) 5, CK7, CK20, CK AE1/AE3, and p63 (Figure 3). The culmination of features including the large tumor size, immunohistochemical staining pattern, and mild pleomorphism with focal invasion into the soft tissue supported the diagnosis of hidradenocarcinoma.

Hidradenocarcinoma is an exceedingly rare malignant tumor of eccrine and/or apocrine origin.¹ It accounts for less than 0.001% of all tumors and 1 of 13,000 skin biopsies.² It usually arises in the head and neck region and most commonly affects older adults aged 50 to 70 years.³ The size of hidradenocarcinomas can vary; however, they typically are large, often growing to be greater than 5 cm in diameter.² It tends to be an aggressive tumor that generally spreads to regional lymph nodes and distant viscera.⁴ Although it most commonly arises de novo, it may occasionally derive from a benign hidradenoma.¹ The diagnosis of hidradenocarcinoma is made based on the tumor’s morphologic and pathologic characteristics. Histologically, it is characterized by an infiltrative and invasive proliferation of lobules made of large clear cells with atypical mitotic figures and nuclear pleomorphism as well as immunohistochemical features displaying various positive markers, such as carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, and CKs AE1/AE3 and 5/6.² Invasion of the adjacent soft tissue can be present and helps to confirm the diagnosis.

The differential diagnosis for hidradenocarcinoma primarily is the benign hidradenoma, which is similar both clinically and histologically with a few important differences. Hidradenocarcinomas often are larger and ulcerated. Histologically, they usually are more pleomorphic with the presence of mitotic figures in clear cells and tend to invade locally into the surrounding soft tissue. Other similar lesions such as spiradenoma, Merkel cell carcinoma, lymphangioma, cutaneous Crohn disease, tumors metastatic to the skin, and metastatic clear cell carcinomas originating from other organs also are included in the differential diagnosis.²

Spiradenomas are dermal tumors originating from the sweat glands. They typically present as bluish, painful, solitary nodules on the ventral surfaces of the upper body, though multiple nodules also are reported.⁵ Spiradenomas manifest as a central constellation of pale large cells surrounded by small, dark, basaloid cells containing hyperchromatic nuclei. The microscopic appearance of the blue basaloid cells contrasts with the clear cells seen in hidradenoma.⁵

Merkel cell carcinoma is a cutaneous neuroendocrine tumor affecting elderly or immunosuppressed individuals. It arises in sun-exposed areas and often is associated with Merkel cell polyomavirus infection. The histologic features display small and round cells that stain positive for CK8, CK18, CK19, and CK20 but stain negative for CK7, a marker that often is positive in hidradenocarcinoma.⁶

Lymphangioma, particularly cavernous lymphangioma, may resemble the gross appearance of hidradenoma/ hidradenocarcinoma. It usually presents as irregular clear blue papules and nodules in the skin and subcutaneous tissue.⁷ The key histopathologic finding in this tumor is the endothelium-lined channels that stain positive for D2-40, a lymphatic endothelium marker.^7,8

Cutaneous Crohn disease is classified as noncaseating granulomatous skin lesions that are noncontinuous with the gastrointestinal tract.⁹ Clinical presentations in addition to skin edema include erythematous plaques, ulcerations, and erosions. Histopathology reveals sterile noncaseating granulomas made of Langerhans giant cells, epithelioid histocytes, and plasma cells.⁹

Metastatic clear cell carcinomas, such as renal cell carcinoma, can be differentiated by a history of primary carcinoma, demonstration of histologic vascular stroma, and other features related to metastatic clear cell carcinoma.²

There are no well-established therapeutic guidelines for hidradenocarcinoma. Wide local excision with margins greater than 2 cm is the preferred initial treatment and often is performed in conjunction with sentinel lymph node biopsy. External beam radiotherapy and adjunctive chemotherapy have been used for tumors that could not be surgically cleared. However, the efficacy of these treatments has not been well established.² Targeted therapies recently have emerged as an alternative treatment choice for hidradenocarcinoma due to the utilization of immunohistochemical and genomic testing. The discovery of specific gene mutations or the expression of hormonal receptors in this tumor have paved the way for targeting HER2-expressing hidradenocarcinomas with trastuzumab and those expressing estrogen receptor with the estrogen receptor inhibitor tamoxifen.¹ Epidermal growth factor receptor inhibitors and PI3K/Akt/mTOR (phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin) pathway inhibitors also have been used to target various signal transduction pathways.²

Wide excision with 2.5-cm margins was performed on our patient, and a positron emission tomography– computed tomography scan revealed no metastatic disease. She declined sentinel lymph node biopsy and additional treatment. Due to the risk for recurrence, she was monitored closely with skin examinations and positron emission tomography–computed tomography every 3 months for the first year and every 6 months thereafter. Thus far, she has had no evidence of local or regional recurrence.

The Diagnosis: Hidradenocarcinoma

An excisional biopsy revealed a neoplasm in the dermis with focal invasion into the adjacent soft tissue (Figure 1). The tumor consisted of sheets of cells with cytoplasmic vacuoles and ductal differentiation (Figure 2), as well as cells with mild atypia, mild pleomorphism, rare mitotic figures, and abundant pale cytoplasm. Immunohistochemical staining was positive for cytokeratin (CK) 5, CK7, CK20, CK AE1/AE3, and p63 (Figure 3). The culmination of features including the large tumor size, immunohistochemical staining pattern, and mild pleomorphism with focal invasion into the soft tissue supported the diagnosis of hidradenocarcinoma.

Hidradenocarcinoma is an exceedingly rare malignant tumor of eccrine and/or apocrine origin.¹ It accounts for less than 0.001% of all tumors and 1 of 13,000 skin biopsies.² It usually arises in the head and neck region and most commonly affects older adults aged 50 to 70 years.³ The size of hidradenocarcinomas can vary; however, they typically are large, often growing to be greater than 5 cm in diameter.² It tends to be an aggressive tumor that generally spreads to regional lymph nodes and distant viscera.⁴ Although it most commonly arises de novo, it may occasionally derive from a benign hidradenoma.¹ The diagnosis of hidradenocarcinoma is made based on the tumor’s morphologic and pathologic characteristics. Histologically, it is characterized by an infiltrative and invasive proliferation of lobules made of large clear cells with atypical mitotic figures and nuclear pleomorphism as well as immunohistochemical features displaying various positive markers, such as carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, and CKs AE1/AE3 and 5/6.² Invasion of the adjacent soft tissue can be present and helps to confirm the diagnosis.

The differential diagnosis for hidradenocarcinoma primarily is the benign hidradenoma, which is similar both clinically and histologically with a few important differences. Hidradenocarcinomas often are larger and ulcerated. Histologically, they usually are more pleomorphic with the presence of mitotic figures in clear cells and tend to invade locally into the surrounding soft tissue. Other similar lesions such as spiradenoma, Merkel cell carcinoma, lymphangioma, cutaneous Crohn disease, tumors metastatic to the skin, and metastatic clear cell carcinomas originating from other organs also are included in the differential diagnosis.²

Spiradenomas are dermal tumors originating from the sweat glands. They typically present as bluish, painful, solitary nodules on the ventral surfaces of the upper body, though multiple nodules also are reported.⁵ Spiradenomas manifest as a central constellation of pale large cells surrounded by small, dark, basaloid cells containing hyperchromatic nuclei. The microscopic appearance of the blue basaloid cells contrasts with the clear cells seen in hidradenoma.⁵

Merkel cell carcinoma is a cutaneous neuroendocrine tumor affecting elderly or immunosuppressed individuals. It arises in sun-exposed areas and often is associated with Merkel cell polyomavirus infection. The histologic features display small and round cells that stain positive for CK8, CK18, CK19, and CK20 but stain negative for CK7, a marker that often is positive in hidradenocarcinoma.⁶

Lymphangioma, particularly cavernous lymphangioma, may resemble the gross appearance of hidradenoma/ hidradenocarcinoma. It usually presents as irregular clear blue papules and nodules in the skin and subcutaneous tissue.⁷ The key histopathologic finding in this tumor is the endothelium-lined channels that stain positive for D2-40, a lymphatic endothelium marker.^7,8

Cutaneous Crohn disease is classified as noncaseating granulomatous skin lesions that are noncontinuous with the gastrointestinal tract.⁹ Clinical presentations in addition to skin edema include erythematous plaques, ulcerations, and erosions. Histopathology reveals sterile noncaseating granulomas made of Langerhans giant cells, epithelioid histocytes, and plasma cells.⁹

Metastatic clear cell carcinomas, such as renal cell carcinoma, can be differentiated by a history of primary carcinoma, demonstration of histologic vascular stroma, and other features related to metastatic clear cell carcinoma.²

There are no well-established therapeutic guidelines for hidradenocarcinoma. Wide local excision with margins greater than 2 cm is the preferred initial treatment and often is performed in conjunction with sentinel lymph node biopsy. External beam radiotherapy and adjunctive chemotherapy have been used for tumors that could not be surgically cleared. However, the efficacy of these treatments has not been well established.² Targeted therapies recently have emerged as an alternative treatment choice for hidradenocarcinoma due to the utilization of immunohistochemical and genomic testing. The discovery of specific gene mutations or the expression of hormonal receptors in this tumor have paved the way for targeting HER2-expressing hidradenocarcinomas with trastuzumab and those expressing estrogen receptor with the estrogen receptor inhibitor tamoxifen.¹ Epidermal growth factor receptor inhibitors and PI3K/Akt/mTOR (phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin) pathway inhibitors also have been used to target various signal transduction pathways.²

Wide excision with 2.5-cm margins was performed on our patient, and a positron emission tomography– computed tomography scan revealed no metastatic disease. She declined sentinel lymph node biopsy and additional treatment. Due to the risk for recurrence, she was monitored closely with skin examinations and positron emission tomography–computed tomography every 3 months for the first year and every 6 months thereafter. Thus far, she has had no evidence of local or regional recurrence.