Case Letter

To the Editor:

Capillary malformations (CMs), the most common vascular malformations that can affect the skin,¹ present clinically as macules and patches of various colors, shapes, and sizes. Congenital structural abnormalities are associated with conditions such as Klippel-Trenaunay syndrome (KTS), cutis marmorata telangiectatica congenita (CMTC), and megalencephaly–capillary malformation syndrome.² Diffuse CM with overgrowth (DCMO) of the soft tissue and bones is an established association of CMs; however, diffuse capillary malformation with undergrowth (DCMU) is a more recent term that describes the lesser-recognized counterpart to DCMO.³ Herein, we describe a case of CM with left-sided undergrowth.

An 11-year-old boy presented to our clinic with asymptomatic vascular patterning on the left side of the body that had been present since birth. He previously was diagnosed with congenital right hemihypertrophy. He reported that the areas gradually lightened over time, and he denied any history of ulceration or venous or lymphatic malformations. Additionally, he explained how the left arm and leg have been noticeably smaller than the right extremities throughout his life. Physical examination revealed superficial, violaceous, reticulated patches along the left upper back tracking down the arm, abdomen (Figure 1A), and anterior thigh (Figure 1B) without crossing the midline. A few dilated veins were noted in the same region as the patches. There was no evidence of scarring or depression found in the skin. The right arms and legs were visibly larger compared to the left side (Figure 2A), and there also was macrodactyly of the third digit of the left hand (Figure 2B). Radiography confirmed the limb length discrepancy and showed the right and left legs to measure 73.2 cm and 71.3 cm, respectively. Given the patient’s multifocal reticulated CMs and ipsilateral undergrowth, a diagnosis of DCMU was rendered. The superficial vascular pattern is likely to fade over time, which will partially be hidden by his darker complexion. He also was advised to continue to see an orthopedist to monitor the limb length incongruity. Surgical intervention was not recommended.

It ordinarily is thought that vascular anomalies of a limb may result in hypertrophy due to increased blood flow such as in KTS, but there are occasions where the affected limb(s) are inexplicably smaller.^2,4 Cubiró et al³ observed that in 6 patients with unilateral CMs, all had ipsilateral limb undergrowth. They proposed the term diffuse capillary malformation with undergrowth as a distinct counterpart to DCMO. Diffuse capillary malformation with undergrowth is most similar to CMTC, as both can present with patchy or reticulated capillary staining with ipsilateral limb hypotrophy, but girth more often is affected than length; CMTC also may be associated with dermal atrophy and ulceration.² The lesions of CMTC typically diminish within the first few years of life whereas those in DCMU tend to persist. Patients with KTS also can exhibit soft-tissue and bony undergrowth, which is termed inverse Klippel-Trenaunay syndrome³; however, the lack of the triad of capillary-lymphatic-venous malformation in our patient made this condition less likely. Additionally, it appears that our patient had left-sided undergrowth rather than the previously diagnosed right hemihypertrophy. The ipsilateral macrodactyly of the third digit of the left hand was an interesting observation and contrasted the undergrowth apparent in the rest of the left limb, which could be caused by increased blood flow specifically to the third digit resembling DCMO.⁴

Of note, genetic mutations have been implicated as a cause of vascular malformations and growth abnormalities. Specifically, mutations in the phosphoinositide-3-kinase–AKT pathway have been reported in these cases likely due its role in cell growth, proliferation, and angiogenesis.^3,4 Future studies should investigate genetic associations in patients with DCMU to determine if there is a robust genotypic-phenotypic link.

Although CMs are a common occurrence in pediatric dermatology, CMs with concurrent limb undergrowth are rare. Our patient’s unique features included involvement of both an arm and leg as well as the presence of macrodactyly. We agree with the terminology for DCMU to describe multifocal reticulated vascular patterning with ipsilateral undergrowth.³

To the Editor:

Capillary malformations (CMs), the most common vascular malformations that can affect the skin,¹ present clinically as macules and patches of various colors, shapes, and sizes. Congenital structural abnormalities are associated with conditions such as Klippel-Trenaunay syndrome (KTS), cutis marmorata telangiectatica congenita (CMTC), and megalencephaly–capillary malformation syndrome.² Diffuse CM with overgrowth (DCMO) of the soft tissue and bones is an established association of CMs; however, diffuse capillary malformation with undergrowth (DCMU) is a more recent term that describes the lesser-recognized counterpart to DCMO.³ Herein, we describe a case of CM with left-sided undergrowth.

An 11-year-old boy presented to our clinic with asymptomatic vascular patterning on the left side of the body that had been present since birth. He previously was diagnosed with congenital right hemihypertrophy. He reported that the areas gradually lightened over time, and he denied any history of ulceration or venous or lymphatic malformations. Additionally, he explained how the left arm and leg have been noticeably smaller than the right extremities throughout his life. Physical examination revealed superficial, violaceous, reticulated patches along the left upper back tracking down the arm, abdomen (Figure 1A), and anterior thigh (Figure 1B) without crossing the midline. A few dilated veins were noted in the same region as the patches. There was no evidence of scarring or depression found in the skin. The right arms and legs were visibly larger compared to the left side (Figure 2A), and there also was macrodactyly of the third digit of the left hand (Figure 2B). Radiography confirmed the limb length discrepancy and showed the right and left legs to measure 73.2 cm and 71.3 cm, respectively. Given the patient’s multifocal reticulated CMs and ipsilateral undergrowth, a diagnosis of DCMU was rendered. The superficial vascular pattern is likely to fade over time, which will partially be hidden by his darker complexion. He also was advised to continue to see an orthopedist to monitor the limb length incongruity. Surgical intervention was not recommended.

It ordinarily is thought that vascular anomalies of a limb may result in hypertrophy due to increased blood flow such as in KTS, but there are occasions where the affected limb(s) are inexplicably smaller.^2,4 Cubiró et al³ observed that in 6 patients with unilateral CMs, all had ipsilateral limb undergrowth. They proposed the term diffuse capillary malformation with undergrowth as a distinct counterpart to DCMO. Diffuse capillary malformation with undergrowth is most similar to CMTC, as both can present with patchy or reticulated capillary staining with ipsilateral limb hypotrophy, but girth more often is affected than length; CMTC also may be associated with dermal atrophy and ulceration.² The lesions of CMTC typically diminish within the first few years of life whereas those in DCMU tend to persist. Patients with KTS also can exhibit soft-tissue and bony undergrowth, which is termed inverse Klippel-Trenaunay syndrome³; however, the lack of the triad of capillary-lymphatic-venous malformation in our patient made this condition less likely. Additionally, it appears that our patient had left-sided undergrowth rather than the previously diagnosed right hemihypertrophy. The ipsilateral macrodactyly of the third digit of the left hand was an interesting observation and contrasted the undergrowth apparent in the rest of the left limb, which could be caused by increased blood flow specifically to the third digit resembling DCMO.⁴

Of note, genetic mutations have been implicated as a cause of vascular malformations and growth abnormalities. Specifically, mutations in the phosphoinositide-3-kinase–AKT pathway have been reported in these cases likely due its role in cell growth, proliferation, and angiogenesis.^3,4 Future studies should investigate genetic associations in patients with DCMU to determine if there is a robust genotypic-phenotypic link.

Although CMs are a common occurrence in pediatric dermatology, CMs with concurrent limb undergrowth are rare. Our patient’s unique features included involvement of both an arm and leg as well as the presence of macrodactyly. We agree with the terminology for DCMU to describe multifocal reticulated vascular patterning with ipsilateral undergrowth.³

To the Editor:

Capillary malformations (CMs), the most common vascular malformations that can affect the skin,¹ present clinically as macules and patches of various colors, shapes, and sizes. Congenital structural abnormalities are associated with conditions such as Klippel-Trenaunay syndrome (KTS), cutis marmorata telangiectatica congenita (CMTC), and megalencephaly–capillary malformation syndrome.² Diffuse CM with overgrowth (DCMO) of the soft tissue and bones is an established association of CMs; however, diffuse capillary malformation with undergrowth (DCMU) is a more recent term that describes the lesser-recognized counterpart to DCMO.³ Herein, we describe a case of CM with left-sided undergrowth.

An 11-year-old boy presented to our clinic with asymptomatic vascular patterning on the left side of the body that had been present since birth. He previously was diagnosed with congenital right hemihypertrophy. He reported that the areas gradually lightened over time, and he denied any history of ulceration or venous or lymphatic malformations. Additionally, he explained how the left arm and leg have been noticeably smaller than the right extremities throughout his life. Physical examination revealed superficial, violaceous, reticulated patches along the left upper back tracking down the arm, abdomen (Figure 1A), and anterior thigh (Figure 1B) without crossing the midline. A few dilated veins were noted in the same region as the patches. There was no evidence of scarring or depression found in the skin. The right arms and legs were visibly larger compared to the left side (Figure 2A), and there also was macrodactyly of the third digit of the left hand (Figure 2B). Radiography confirmed the limb length discrepancy and showed the right and left legs to measure 73.2 cm and 71.3 cm, respectively. Given the patient’s multifocal reticulated CMs and ipsilateral undergrowth, a diagnosis of DCMU was rendered. The superficial vascular pattern is likely to fade over time, which will partially be hidden by his darker complexion. He also was advised to continue to see an orthopedist to monitor the limb length incongruity. Surgical intervention was not recommended.

It ordinarily is thought that vascular anomalies of a limb may result in hypertrophy due to increased blood flow such as in KTS, but there are occasions where the affected limb(s) are inexplicably smaller.^2,4 Cubiró et al³ observed that in 6 patients with unilateral CMs, all had ipsilateral limb undergrowth. They proposed the term diffuse capillary malformation with undergrowth as a distinct counterpart to DCMO. Diffuse capillary malformation with undergrowth is most similar to CMTC, as both can present with patchy or reticulated capillary staining with ipsilateral limb hypotrophy, but girth more often is affected than length; CMTC also may be associated with dermal atrophy and ulceration.² The lesions of CMTC typically diminish within the first few years of life whereas those in DCMU tend to persist. Patients with KTS also can exhibit soft-tissue and bony undergrowth, which is termed inverse Klippel-Trenaunay syndrome³; however, the lack of the triad of capillary-lymphatic-venous malformation in our patient made this condition less likely. Additionally, it appears that our patient had left-sided undergrowth rather than the previously diagnosed right hemihypertrophy. The ipsilateral macrodactyly of the third digit of the left hand was an interesting observation and contrasted the undergrowth apparent in the rest of the left limb, which could be caused by increased blood flow specifically to the third digit resembling DCMO.⁴

Of note, genetic mutations have been implicated as a cause of vascular malformations and growth abnormalities. Specifically, mutations in the phosphoinositide-3-kinase–AKT pathway have been reported in these cases likely due its role in cell growth, proliferation, and angiogenesis.^3,4 Future studies should investigate genetic associations in patients with DCMU to determine if there is a robust genotypic-phenotypic link.

Although CMs are a common occurrence in pediatric dermatology, CMs with concurrent limb undergrowth are rare. Our patient’s unique features included involvement of both an arm and leg as well as the presence of macrodactyly. We agree with the terminology for DCMU to describe multifocal reticulated vascular patterning with ipsilateral undergrowth.³

To the Editor:

Neutrophilic dermatosis of the dorsal hand (NDDH) is an uncommon reactive neutrophilic dermatosis that presents as a painful, enlarging, ulcerative nodule. It often is misdiagnosed and initially treated as an infection. Similar to other neutrophilic dermatoses, it is associated with underlying infections, inflammatory conditions, and malignancies. Neutrophilic dermatosis of the dorsal hand is considered a subset of Sweet syndrome (SS); we highlight similarities and differences between NDDH and SS, reporting the case of a 66-year-old man without systemic symptoms who developed NDDH on the right hand.

A 66-year-old man presented with a progressively enlarging, painful, ulcerative, 2-cm nodule on the right hand following mechanical trauma 2 weeks prior (Figure 1). He was afebrile with no remarkable medical history. Laboratory evaluation revealed an erythrocyte sedimentation rate (ESR) of 20 mm/h (reference range, 0-10 mm/h) and C-reactive protein (CRP) level of 3.52 mg/dL (reference range, 0-0.5 mg/dL) without leukocytosis; both were not remarkably elevated when adjusted for age.^1,2 The clinical differential diagnosis was broad and included pyoderma with evolving cellulitis, neutrophilic dermatosis, atypical mycobacterial infection, subcutaneous or deep fungal infection, squamous cell carcinoma, cutaneous lymphoma, and metastasis. Due to the rapid development of the lesion, initial treatment focused on a bacterial infection, but there was no improvement on antibiotics and wound cultures were negative. The ulcerative nodule was biopsied, and histopathology demonstrated abundant neutrophilic inflammation, endothelial swelling, and leukocytoclasis without microorganisms (Figure 2). Tissue cultures for bacteria, fungi, and atypical mycobacteria were negative. A diagnosis of NDDH was made based on clinical and histologic findings. The wound improved with a 3-week course of oral prednisone.

Neutrophilic dermatosis of the dorsal hand is a subset of reactive neutrophilic dermatoses, which includes SS (acute febrile neutrophilic dermatosis) and pyoderma gangrenosum. It is described as a localized variant of SS, with similar associated underlying inflammatory, neoplastic conditions and laboratory findings.³ However, NDDH has characteristic features that differ from classic SS. Neutrophilic dermatosis of the dorsal hand typically presents as painful papules, pustules, or ulcers that progress to become larger ulcers, plaques, and nodules. The clinical appearance may more closely resemble pyoderma gangrenosum or atypical SS, with ulceration frequently present. Pathergy also may be demonstrated in NDDH, similar to our patient. The average age of presentation for NDDH is 60 years, which is older than the average age for SS or pyoderma gangrenosum.³ Similar to other neutrophilic dermatoses, NDDH responds well to oral steroids or steroid-sparing immunosuppressants such as dapsone, colchicine, azathioprine, or tetracycline antibiotics.⁴

The criteria for SS are well established^5,6 and may be used for the diagnosis of NDDH, taking into account the localization of lesions to the dorsal aspect of the hands. The diagnostic criteria for SS include fulfillment of both major and at least 2 of 4 minor criteria. The 2 major criteria include rapid presentation of skin lesions and neutrophilic dermal infiltrate on biopsy. Minor criteria are defined as the following: (1) preceding nonspecific respiratory or gastrointestinal tract infection, inflammatory conditions, underlying malignancy, or pregnancy; (2) fever; (3) excellent response to steroids; and (4) 3 of the 4 of the following laboratory abnormalities: elevated CRP, ESR, leukocytosis, or left shift in complete blood cell count. Our patient met both major criteria and only 1 minor criterion—excellent response to systemic corticosteroids. Nofal et al⁷ advocated for revised diagnostic criteria for SS, with one suggestion utilizing only the 2 major criteria being necessary for diagnosis. Given that serum inflammatory markers may not be as elevated in NDDH compared to SS,^3,7,8 meeting the major criteria alone may be a better way to diagnose NDDH, as in our patient.

Our patient presented with an expanding ulcerating nodule on the hand that elicited a wide list of differential diagnoses to include infections and neoplasms. Rapid development, localization to the dorsal aspect of the hand, and treatment resistance to antibiotics may help the clinician consider a diagnosis of NDDH, which should be confirmed by a biopsy. Similar to other neutrophilic dermatoses, an underlying malignancy or inflammatory condition should be sought out. Neutrophilic dermatosis of the dorsal hand responds well to systemic steroids, though recurrences may occur.

To the Editor:

Neutrophilic dermatosis of the dorsal hand (NDDH) is an uncommon reactive neutrophilic dermatosis that presents as a painful, enlarging, ulcerative nodule. It often is misdiagnosed and initially treated as an infection. Similar to other neutrophilic dermatoses, it is associated with underlying infections, inflammatory conditions, and malignancies. Neutrophilic dermatosis of the dorsal hand is considered a subset of Sweet syndrome (SS); we highlight similarities and differences between NDDH and SS, reporting the case of a 66-year-old man without systemic symptoms who developed NDDH on the right hand.

A 66-year-old man presented with a progressively enlarging, painful, ulcerative, 2-cm nodule on the right hand following mechanical trauma 2 weeks prior (Figure 1). He was afebrile with no remarkable medical history. Laboratory evaluation revealed an erythrocyte sedimentation rate (ESR) of 20 mm/h (reference range, 0-10 mm/h) and C-reactive protein (CRP) level of 3.52 mg/dL (reference range, 0-0.5 mg/dL) without leukocytosis; both were not remarkably elevated when adjusted for age.^1,2 The clinical differential diagnosis was broad and included pyoderma with evolving cellulitis, neutrophilic dermatosis, atypical mycobacterial infection, subcutaneous or deep fungal infection, squamous cell carcinoma, cutaneous lymphoma, and metastasis. Due to the rapid development of the lesion, initial treatment focused on a bacterial infection, but there was no improvement on antibiotics and wound cultures were negative. The ulcerative nodule was biopsied, and histopathology demonstrated abundant neutrophilic inflammation, endothelial swelling, and leukocytoclasis without microorganisms (Figure 2). Tissue cultures for bacteria, fungi, and atypical mycobacteria were negative. A diagnosis of NDDH was made based on clinical and histologic findings. The wound improved with a 3-week course of oral prednisone.

Neutrophilic dermatosis of the dorsal hand is a subset of reactive neutrophilic dermatoses, which includes SS (acute febrile neutrophilic dermatosis) and pyoderma gangrenosum. It is described as a localized variant of SS, with similar associated underlying inflammatory, neoplastic conditions and laboratory findings.³ However, NDDH has characteristic features that differ from classic SS. Neutrophilic dermatosis of the dorsal hand typically presents as painful papules, pustules, or ulcers that progress to become larger ulcers, plaques, and nodules. The clinical appearance may more closely resemble pyoderma gangrenosum or atypical SS, with ulceration frequently present. Pathergy also may be demonstrated in NDDH, similar to our patient. The average age of presentation for NDDH is 60 years, which is older than the average age for SS or pyoderma gangrenosum.³ Similar to other neutrophilic dermatoses, NDDH responds well to oral steroids or steroid-sparing immunosuppressants such as dapsone, colchicine, azathioprine, or tetracycline antibiotics.⁴

The criteria for SS are well established^5,6 and may be used for the diagnosis of NDDH, taking into account the localization of lesions to the dorsal aspect of the hands. The diagnostic criteria for SS include fulfillment of both major and at least 2 of 4 minor criteria. The 2 major criteria include rapid presentation of skin lesions and neutrophilic dermal infiltrate on biopsy. Minor criteria are defined as the following: (1) preceding nonspecific respiratory or gastrointestinal tract infection, inflammatory conditions, underlying malignancy, or pregnancy; (2) fever; (3) excellent response to steroids; and (4) 3 of the 4 of the following laboratory abnormalities: elevated CRP, ESR, leukocytosis, or left shift in complete blood cell count. Our patient met both major criteria and only 1 minor criterion—excellent response to systemic corticosteroids. Nofal et al⁷ advocated for revised diagnostic criteria for SS, with one suggestion utilizing only the 2 major criteria being necessary for diagnosis. Given that serum inflammatory markers may not be as elevated in NDDH compared to SS,^3,7,8 meeting the major criteria alone may be a better way to diagnose NDDH, as in our patient.

Our patient presented with an expanding ulcerating nodule on the hand that elicited a wide list of differential diagnoses to include infections and neoplasms. Rapid development, localization to the dorsal aspect of the hand, and treatment resistance to antibiotics may help the clinician consider a diagnosis of NDDH, which should be confirmed by a biopsy. Similar to other neutrophilic dermatoses, an underlying malignancy or inflammatory condition should be sought out. Neutrophilic dermatosis of the dorsal hand responds well to systemic steroids, though recurrences may occur.

To the Editor:

Neutrophilic dermatosis of the dorsal hand (NDDH) is an uncommon reactive neutrophilic dermatosis that presents as a painful, enlarging, ulcerative nodule. It often is misdiagnosed and initially treated as an infection. Similar to other neutrophilic dermatoses, it is associated with underlying infections, inflammatory conditions, and malignancies. Neutrophilic dermatosis of the dorsal hand is considered a subset of Sweet syndrome (SS); we highlight similarities and differences between NDDH and SS, reporting the case of a 66-year-old man without systemic symptoms who developed NDDH on the right hand.

A 66-year-old man presented with a progressively enlarging, painful, ulcerative, 2-cm nodule on the right hand following mechanical trauma 2 weeks prior (Figure 1). He was afebrile with no remarkable medical history. Laboratory evaluation revealed an erythrocyte sedimentation rate (ESR) of 20 mm/h (reference range, 0-10 mm/h) and C-reactive protein (CRP) level of 3.52 mg/dL (reference range, 0-0.5 mg/dL) without leukocytosis; both were not remarkably elevated when adjusted for age.^1,2 The clinical differential diagnosis was broad and included pyoderma with evolving cellulitis, neutrophilic dermatosis, atypical mycobacterial infection, subcutaneous or deep fungal infection, squamous cell carcinoma, cutaneous lymphoma, and metastasis. Due to the rapid development of the lesion, initial treatment focused on a bacterial infection, but there was no improvement on antibiotics and wound cultures were negative. The ulcerative nodule was biopsied, and histopathology demonstrated abundant neutrophilic inflammation, endothelial swelling, and leukocytoclasis without microorganisms (Figure 2). Tissue cultures for bacteria, fungi, and atypical mycobacteria were negative. A diagnosis of NDDH was made based on clinical and histologic findings. The wound improved with a 3-week course of oral prednisone.

Neutrophilic dermatosis of the dorsal hand is a subset of reactive neutrophilic dermatoses, which includes SS (acute febrile neutrophilic dermatosis) and pyoderma gangrenosum. It is described as a localized variant of SS, with similar associated underlying inflammatory, neoplastic conditions and laboratory findings.³ However, NDDH has characteristic features that differ from classic SS. Neutrophilic dermatosis of the dorsal hand typically presents as painful papules, pustules, or ulcers that progress to become larger ulcers, plaques, and nodules. The clinical appearance may more closely resemble pyoderma gangrenosum or atypical SS, with ulceration frequently present. Pathergy also may be demonstrated in NDDH, similar to our patient. The average age of presentation for NDDH is 60 years, which is older than the average age for SS or pyoderma gangrenosum.³ Similar to other neutrophilic dermatoses, NDDH responds well to oral steroids or steroid-sparing immunosuppressants such as dapsone, colchicine, azathioprine, or tetracycline antibiotics.⁴

The criteria for SS are well established^5,6 and may be used for the diagnosis of NDDH, taking into account the localization of lesions to the dorsal aspect of the hands. The diagnostic criteria for SS include fulfillment of both major and at least 2 of 4 minor criteria. The 2 major criteria include rapid presentation of skin lesions and neutrophilic dermal infiltrate on biopsy. Minor criteria are defined as the following: (1) preceding nonspecific respiratory or gastrointestinal tract infection, inflammatory conditions, underlying malignancy, or pregnancy; (2) fever; (3) excellent response to steroids; and (4) 3 of the 4 of the following laboratory abnormalities: elevated CRP, ESR, leukocytosis, or left shift in complete blood cell count. Our patient met both major criteria and only 1 minor criterion—excellent response to systemic corticosteroids. Nofal et al⁷ advocated for revised diagnostic criteria for SS, with one suggestion utilizing only the 2 major criteria being necessary for diagnosis. Given that serum inflammatory markers may not be as elevated in NDDH compared to SS,^3,7,8 meeting the major criteria alone may be a better way to diagnose NDDH, as in our patient.

Our patient presented with an expanding ulcerating nodule on the hand that elicited a wide list of differential diagnoses to include infections and neoplasms. Rapid development, localization to the dorsal aspect of the hand, and treatment resistance to antibiotics may help the clinician consider a diagnosis of NDDH, which should be confirmed by a biopsy. Similar to other neutrophilic dermatoses, an underlying malignancy or inflammatory condition should be sought out. Neutrophilic dermatosis of the dorsal hand responds well to systemic steroids, though recurrences may occur.

To the Editor:

Biologic medications are increasingly utilized in adults with moderate to severe atopic dermatitis (AD) that is inadequately controlled with topical medication. By targeting the IL-4 receptor alpha subunit, dupilumab inhibits the biologic effects of IL-4 and IL-13, resulting in remarkable improvement in disease and quality of life for many patients with refractory AD.¹

In 2017, the US Food and Drug Administration approved dupilumab for use in AD, asthma, and chronic rhinosinusitis. However, there is evidence of the drug’s off-label efficacy in conditions such as eosinophilic annular erythema.² We present a patient with dyshidrotic eczema treated with dupilumab who experienced contemporaneous secondary improvement in chronic eosinophilic pneumonia (CEP) and interstitial lung disease (ILD).

A 45-year-old man was referred to our dermatology clinic for chronic hand dermatitis refractory to increasing strengths of topical corticosteroids. He had a history of progressive shortness of breath of unknown cause, which began 2 years prior, and he was being followed at our institution’s ILD clinic. Earlier pulmonary function testing revealed a restrictive pattern with interstitial infiltrates seen on chest computed tomography. A lung biopsy demonstrated features of fibrotic nonspecific interstitial pneumonitis with superimposed eosinophilic pneumonia. His pulmonary symptoms had progressively worsened; over a period of several months, the supplemental oxygen requirement had increased to 6 L at rest and 12 L upon exertion. Prednisone therapy was initiated, which alleviated respiratory symptoms; however, the patient was unable to tolerate a gradual wean of the medication, which rendered him steroid dependent at 30 mg/d.

Along with respiratory symptoms, the patient reported symptoms consistent with an autoimmune process, including dry eyes. Muscle weakness and tenderness also were noted. Ultimately, a diagnosis of anti–PL-7 (anti-threonyl-transfer RNA synthetase) antisynthetase syndrome was rendered by identification of anti–PL-7 antibodies and an elevated level of creatinine kinase.

Physical examination at our clinic revealed subtle palmar scaling on the hands and multiple small clear vesicles on the lateral aspects of the digits (Figure, A), consistent with dyshidrotic eczema. He initially was treated with clobetasol propionate ointment 0.05%. Despite adherence to this high-potency topical corticosteroid, he experienced only minimal improvement over a period of 3 months. Dupilumab was started at standard dosing—600 mg at initiation, followed by 300 mg every 2 weeks. The patient reported rapid improvement in dyshidrotic eczema over several months with near-complete resolution (Figure, B).

Concurrent with initiation and continued use of dupilumab, without other changes in his medication regimen, the patient noted gradual improvement in respiratory symptoms. At 6-month follow-up he reported notable improvement in respiratory function and quality of life. He then tolerated a gradual wean of prednisone to 10 mg/d, with a similar reduction in supplemental oxygen.

Off-label use of dupilumab for various eosinophilic conditions has shown promising efficacy. Our patient experienced improvement in CEP shortly after initiation of dupilumab, enabling weaning of prednisone, which has a well established adverse effect profile associated with long term use.^3,4 In comparison, dupilumab generally is well tolerated, with rare ophthalmologic complications and injection-site reactions.⁵

One case report suggested that CEP may represent a potential rare adverse effect of dupilumab initiation.⁶ However, prior to initiation of dupilumab, that patient had poorly controlled asthma requiring frequent oral corticosteroid therapy. It is possible that CEP was subclinical prior to initiation of dupilumab and became more noticeable once the patient was weaned from corticosteroids, which had served as an indirect treatment.⁶ Nonetheless, more research is needed to definitively establish the efficacy of dupilumab in CEP prior to more widespread use.

Irrespective of the potential efficacy of dupilumab for the treatment of CEP, our case highlights the growing body of evidence that dupilumab should be considered in the treatment of dyshidrotic eczema, particularly in cases refractory to topical treatment.⁷ When a systemic medication is preferred, dupilumab likely represents an option with a relatively well-tolerated adverse effect profile compared to traditional systemic treatments for dyshidrotic eczema.

To the Editor:

Biologic medications are increasingly utilized in adults with moderate to severe atopic dermatitis (AD) that is inadequately controlled with topical medication. By targeting the IL-4 receptor alpha subunit, dupilumab inhibits the biologic effects of IL-4 and IL-13, resulting in remarkable improvement in disease and quality of life for many patients with refractory AD.¹

In 2017, the US Food and Drug Administration approved dupilumab for use in AD, asthma, and chronic rhinosinusitis. However, there is evidence of the drug’s off-label efficacy in conditions such as eosinophilic annular erythema.² We present a patient with dyshidrotic eczema treated with dupilumab who experienced contemporaneous secondary improvement in chronic eosinophilic pneumonia (CEP) and interstitial lung disease (ILD).

A 45-year-old man was referred to our dermatology clinic for chronic hand dermatitis refractory to increasing strengths of topical corticosteroids. He had a history of progressive shortness of breath of unknown cause, which began 2 years prior, and he was being followed at our institution’s ILD clinic. Earlier pulmonary function testing revealed a restrictive pattern with interstitial infiltrates seen on chest computed tomography. A lung biopsy demonstrated features of fibrotic nonspecific interstitial pneumonitis with superimposed eosinophilic pneumonia. His pulmonary symptoms had progressively worsened; over a period of several months, the supplemental oxygen requirement had increased to 6 L at rest and 12 L upon exertion. Prednisone therapy was initiated, which alleviated respiratory symptoms; however, the patient was unable to tolerate a gradual wean of the medication, which rendered him steroid dependent at 30 mg/d.

Along with respiratory symptoms, the patient reported symptoms consistent with an autoimmune process, including dry eyes. Muscle weakness and tenderness also were noted. Ultimately, a diagnosis of anti–PL-7 (anti-threonyl-transfer RNA synthetase) antisynthetase syndrome was rendered by identification of anti–PL-7 antibodies and an elevated level of creatinine kinase.

Physical examination at our clinic revealed subtle palmar scaling on the hands and multiple small clear vesicles on the lateral aspects of the digits (Figure, A), consistent with dyshidrotic eczema. He initially was treated with clobetasol propionate ointment 0.05%. Despite adherence to this high-potency topical corticosteroid, he experienced only minimal improvement over a period of 3 months. Dupilumab was started at standard dosing—600 mg at initiation, followed by 300 mg every 2 weeks. The patient reported rapid improvement in dyshidrotic eczema over several months with near-complete resolution (Figure, B).

Concurrent with initiation and continued use of dupilumab, without other changes in his medication regimen, the patient noted gradual improvement in respiratory symptoms. At 6-month follow-up he reported notable improvement in respiratory function and quality of life. He then tolerated a gradual wean of prednisone to 10 mg/d, with a similar reduction in supplemental oxygen.

Off-label use of dupilumab for various eosinophilic conditions has shown promising efficacy. Our patient experienced improvement in CEP shortly after initiation of dupilumab, enabling weaning of prednisone, which has a well established adverse effect profile associated with long term use.^3,4 In comparison, dupilumab generally is well tolerated, with rare ophthalmologic complications and injection-site reactions.⁵

One case report suggested that CEP may represent a potential rare adverse effect of dupilumab initiation.⁶ However, prior to initiation of dupilumab, that patient had poorly controlled asthma requiring frequent oral corticosteroid therapy. It is possible that CEP was subclinical prior to initiation of dupilumab and became more noticeable once the patient was weaned from corticosteroids, which had served as an indirect treatment.⁶ Nonetheless, more research is needed to definitively establish the efficacy of dupilumab in CEP prior to more widespread use.

Irrespective of the potential efficacy of dupilumab for the treatment of CEP, our case highlights the growing body of evidence that dupilumab should be considered in the treatment of dyshidrotic eczema, particularly in cases refractory to topical treatment.⁷ When a systemic medication is preferred, dupilumab likely represents an option with a relatively well-tolerated adverse effect profile compared to traditional systemic treatments for dyshidrotic eczema.

To the Editor:

Biologic medications are increasingly utilized in adults with moderate to severe atopic dermatitis (AD) that is inadequately controlled with topical medication. By targeting the IL-4 receptor alpha subunit, dupilumab inhibits the biologic effects of IL-4 and IL-13, resulting in remarkable improvement in disease and quality of life for many patients with refractory AD.¹

In 2017, the US Food and Drug Administration approved dupilumab for use in AD, asthma, and chronic rhinosinusitis. However, there is evidence of the drug’s off-label efficacy in conditions such as eosinophilic annular erythema.² We present a patient with dyshidrotic eczema treated with dupilumab who experienced contemporaneous secondary improvement in chronic eosinophilic pneumonia (CEP) and interstitial lung disease (ILD).

A 45-year-old man was referred to our dermatology clinic for chronic hand dermatitis refractory to increasing strengths of topical corticosteroids. He had a history of progressive shortness of breath of unknown cause, which began 2 years prior, and he was being followed at our institution’s ILD clinic. Earlier pulmonary function testing revealed a restrictive pattern with interstitial infiltrates seen on chest computed tomography. A lung biopsy demonstrated features of fibrotic nonspecific interstitial pneumonitis with superimposed eosinophilic pneumonia. His pulmonary symptoms had progressively worsened; over a period of several months, the supplemental oxygen requirement had increased to 6 L at rest and 12 L upon exertion. Prednisone therapy was initiated, which alleviated respiratory symptoms; however, the patient was unable to tolerate a gradual wean of the medication, which rendered him steroid dependent at 30 mg/d.

Along with respiratory symptoms, the patient reported symptoms consistent with an autoimmune process, including dry eyes. Muscle weakness and tenderness also were noted. Ultimately, a diagnosis of anti–PL-7 (anti-threonyl-transfer RNA synthetase) antisynthetase syndrome was rendered by identification of anti–PL-7 antibodies and an elevated level of creatinine kinase.

Physical examination at our clinic revealed subtle palmar scaling on the hands and multiple small clear vesicles on the lateral aspects of the digits (Figure, A), consistent with dyshidrotic eczema. He initially was treated with clobetasol propionate ointment 0.05%. Despite adherence to this high-potency topical corticosteroid, he experienced only minimal improvement over a period of 3 months. Dupilumab was started at standard dosing—600 mg at initiation, followed by 300 mg every 2 weeks. The patient reported rapid improvement in dyshidrotic eczema over several months with near-complete resolution (Figure, B).

Concurrent with initiation and continued use of dupilumab, without other changes in his medication regimen, the patient noted gradual improvement in respiratory symptoms. At 6-month follow-up he reported notable improvement in respiratory function and quality of life. He then tolerated a gradual wean of prednisone to 10 mg/d, with a similar reduction in supplemental oxygen.

Off-label use of dupilumab for various eosinophilic conditions has shown promising efficacy. Our patient experienced improvement in CEP shortly after initiation of dupilumab, enabling weaning of prednisone, which has a well established adverse effect profile associated with long term use.^3,4 In comparison, dupilumab generally is well tolerated, with rare ophthalmologic complications and injection-site reactions.⁵

One case report suggested that CEP may represent a potential rare adverse effect of dupilumab initiation.⁶ However, prior to initiation of dupilumab, that patient had poorly controlled asthma requiring frequent oral corticosteroid therapy. It is possible that CEP was subclinical prior to initiation of dupilumab and became more noticeable once the patient was weaned from corticosteroids, which had served as an indirect treatment.⁶ Nonetheless, more research is needed to definitively establish the efficacy of dupilumab in CEP prior to more widespread use.

Irrespective of the potential efficacy of dupilumab for the treatment of CEP, our case highlights the growing body of evidence that dupilumab should be considered in the treatment of dyshidrotic eczema, particularly in cases refractory to topical treatment.⁷ When a systemic medication is preferred, dupilumab likely represents an option with a relatively well-tolerated adverse effect profile compared to traditional systemic treatments for dyshidrotic eczema.

To the Editor:

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the pilosebaceous unit that occurs in concert with elevations of various cytokines, including tumor necrosis factor α (TNF-α), IL-1β, IL-10, and IL-17.^1,2 Adalimumab is a TNF-α inhibitor approved by the US Food and Drug Administration for the treatment of HS. Although TNF-α inhibitors are effective for many immune-mediated inflammatory disorders, paradoxical drug reactions have been reported following treatment with these agents.^3-6 True paradoxical drug reactions likely are immune mediated and directly lead to new onset of a pathologic condition that would otherwise respond to that drug. For example, there are reports of rheumatoid arthritis patients who were treated with a TNF-α inhibitor and developed psoriatic skin lesions.^3,6 Paradoxical drug reactions also have been reported with acute-onset inflammatory bowel disease and HS or less commonly pyoderma gangrenosum (PG), uveitis, granulomatous reactions, and vasculitis.^4,5 We present the case of a patient with HS who was treated with a TNF-α inhibitor and developed 2 distinct paradoxical drug reactions. We also provide an overview of paradoxical drug reactions associated with TNF-α inhibitors.

A 38-year-old woman developed a painful “boil” on the right leg that was previously treated in the emergency department with incision and drainage as well as oral clindamycin for 7 days, but the lesion spread and continued to worsen. She had a history of HS in the axillae and groin region that had been present since 12 years of age. The condition was poorly controlled despite multiple courses of oral antibiotics and surgical resections. An oral contraceptive also was attempted, but the patient discontinued treatment when liver enzyme levels became elevated. The patient had no other notable medical history, including skin disease. There was a family history of HS in her father and a sibling. Seeking more effective treatment, the patient was offered adalimumab approximately 4 months prior to clinical presentation and agreed to start a course of the drug. She received a loading dose of 160 mg on day 1 and 80 mg on day 15 followed by a maintenance dosage of 40 mg weekly. She experienced improvement in HS symptoms after 3 months on adalimumab; however, she developed scaly pruritic patches on the scalp, arms, and legs that were consistent with psoriasis. Because of the absence of a personal or family history of psoriasis, the patient was informed of the probability of paradoxical psoriasis resulting from adalimumab. She elected to continue adalimumab because of the improvement in HS symptoms, and the psoriatic lesions were mild and adequately controlled with a topical steroid.

At the current presentation 1 month later, physical examination revealed a large indurated and ulcerated area with jagged edges at the incision and drainage site (Figure 1). Pyoderma gangrenosum was clinically suspected; a biopsy was performed, and the patient was started on oral prednisone. At 2-week follow-up, the ulcer was found to be rapidly resolving with prednisone and healing with cribriform scarring (Figure 2). Histopathology revealed an undermining neutrophilic inflammatory process that was consistent with PG. A diagnosis of PG was made based on previously published criteria⁷ and the following major/minor criteria in the patient: pathology; absence of infection on histologic analysis; history of pathergy related to worsening ulceration at the site of incision and drainage of the initial boil; clinical findings of an ulcer with peripheral violaceous erythema; undermined borders and tenderness at the site; and rapid resolution of the ulcer with prednisone.

Cessation of adalimumab gradually led to clearance of both psoriasiform lesions and PG; however, HS lesions persisted. At 2-month follow-up, the patient remained clear of new psoriatic and PG lesions. Alternative treatment options for HS, including isotretinoin and other biologic agents, were discussed with the patient. She was subsequently lost to follow-up.

Although the precise pathogenesis of HS is unclear, both genetic abnormalities of the pilosebaceous unit and a dysregulated immune reaction appear to lead to the clinical characteristics of chronic inflammation and scarring seen in HS. A key effector appears to be helper T-cell (T_H17) lymphocyte activation, with increased secretion of TNF-α, IL-1β, and IL-17.^1,2 In turn, IL-17 induces higher expression of TNF-α, leading to a persistent cycle of inflammation. Peripheral recruitment of IL-17–producing neutrophils also may contribute to chronic inflammation.⁸

Adalimumab is the only US Food and Drug Administration–approved biologic indicated for the treatment of HS. Our patient initially responded to adalimumab with improvement of HS; however, treatment had to be discontinued because of the unusual occurrence of 2 distinct paradoxical reactions in a short span of time. Psoriasis and PG are both considered true paradoxical reactions because primary occurrences of both diseases usually are responsive to treatment with adalimumab.

Tumor necrosis factor α inhibitor–induced psoriasis arises de novo and is estimated to occur in approximately 5% of patients with rheumatoid arthritis.^3,6 Palmoplantar pustular psoriasiform reactions are the most common form of paradoxical psoriasis. Topical medications can be used to treat skin lesions, but systemic treatment is required in many cases. Switching to an alternate class of a biologic, such as an IL-17, IL-12/23, or IL-23 inhibitor, can improve the skin reaction; however, such treatment is inconsistently successful, and paradoxical drug reactions also have been seen with these other classes of biologics.^4,9

Recent studies support distinct immune causes for classical and paradoxical psoriasis. In classical psoriasis, plasmacytoid dendritic cells (pDCs) produce IFN-α, which stimulates conventional dendritic cells to produce TNF-α. However, TNF-α matures both pDCs and conventional dendritic cells; upon maturation, both types of dendritic cells lose the ability to produce IFN-α, thus allowing TNF-α to become dominant.¹⁰ The blockade of TNF-α prevents pDC maturation, leading to uninhibited IFN-α, which appears to drive inflammation in paradoxical psoriasis. In classical psoriasis, oligoclonal dermal CD4⁺ T cells and epidermal CD8⁺ T cells remain, even in resolved skin lesions, and can cause disease recurrence through reactivation of skin-resident memory T cells.¹¹ No relapse of paradoxical psoriasis occurs with discontinuation of anti-TNF-α therapy, which supports the notion of an absence of memory T cells.

The incidence of paradoxical psoriasis in patients receiving a TNF-α inhibitor for HS is unclear.¹² There are case series in which patients who had concurrent psoriasis and HS were successfully treated with a TNF-α inhibitor.¹³ A recently recognized condition—PASH syndrome—encompasses the clinical triad of PG, acne, and HS.¹⁰

Our patient had no history of acne or PG, only a long-standing history of HS. New-onset PG occurred only after a TNF-α inhibitor was initiated. Notably, PASH syndrome has been successfully treated with TNF-α inhibitors, highlighting the shared inflammatory etiology of HS and PG.¹⁴ In patients with concurrent PG and HS, TNF-α inhibitors were more effective for treating PG than for HS.

Pyoderma gangrenosum is an inflammatory disorder that often occurs concomitantly with other conditions, such as inflammatory bowel disease. The exact underlying cause of PG is unclear, but there appears to be both neutrophil and T-cell dysfunction in PG, with excess inflammatory cytokine production (eg, IL-1β, TNF-α, IL-17).¹⁵

The mainstay of treatment of PG is systemic corticosteroids and immunosuppressives, such as cyclosporine. Tumor necrosis factor α inhibitors as well as other interleukin inhibitors are increasingly utilized as potential therapeutic alternatives for PG.^16,17

Unlike paradoxical psoriasis, the underlying cause of paradoxical PG is unclear.^18,19 A similar mechanism may be postulated whereby inhibition of TNF-α leads to excessive activation of alternative inflammatory pathways that result in paradoxical PG. In one study, the prevalence of PG among 68,232 patients with HS was 0.18% compared with 0.01% among those without HS; therefore, patients with HS appear to be more predisposed to PG.²⁰

This case illustrates the complex, often conflicting effects of cytokine inhibition in the paradoxical elicitation of alternative inflammatory disorders as an unintended consequence of the initial cytokine blockade. It is likely that genetic predisposition allows for paradoxical reactions in some patients when there is predominant inhibition of one cytokine in the inflammatory pathway. In rare cases, multiple paradoxical reactions are possible.

To the Editor:

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the pilosebaceous unit that occurs in concert with elevations of various cytokines, including tumor necrosis factor α (TNF-α), IL-1β, IL-10, and IL-17.^1,2 Adalimumab is a TNF-α inhibitor approved by the US Food and Drug Administration for the treatment of HS. Although TNF-α inhibitors are effective for many immune-mediated inflammatory disorders, paradoxical drug reactions have been reported following treatment with these agents.^3-6 True paradoxical drug reactions likely are immune mediated and directly lead to new onset of a pathologic condition that would otherwise respond to that drug. For example, there are reports of rheumatoid arthritis patients who were treated with a TNF-α inhibitor and developed psoriatic skin lesions.^3,6 Paradoxical drug reactions also have been reported with acute-onset inflammatory bowel disease and HS or less commonly pyoderma gangrenosum (PG), uveitis, granulomatous reactions, and vasculitis.^4,5 We present the case of a patient with HS who was treated with a TNF-α inhibitor and developed 2 distinct paradoxical drug reactions. We also provide an overview of paradoxical drug reactions associated with TNF-α inhibitors.

A 38-year-old woman developed a painful “boil” on the right leg that was previously treated in the emergency department with incision and drainage as well as oral clindamycin for 7 days, but the lesion spread and continued to worsen. She had a history of HS in the axillae and groin region that had been present since 12 years of age. The condition was poorly controlled despite multiple courses of oral antibiotics and surgical resections. An oral contraceptive also was attempted, but the patient discontinued treatment when liver enzyme levels became elevated. The patient had no other notable medical history, including skin disease. There was a family history of HS in her father and a sibling. Seeking more effective treatment, the patient was offered adalimumab approximately 4 months prior to clinical presentation and agreed to start a course of the drug. She received a loading dose of 160 mg on day 1 and 80 mg on day 15 followed by a maintenance dosage of 40 mg weekly. She experienced improvement in HS symptoms after 3 months on adalimumab; however, she developed scaly pruritic patches on the scalp, arms, and legs that were consistent with psoriasis. Because of the absence of a personal or family history of psoriasis, the patient was informed of the probability of paradoxical psoriasis resulting from adalimumab. She elected to continue adalimumab because of the improvement in HS symptoms, and the psoriatic lesions were mild and adequately controlled with a topical steroid.

At the current presentation 1 month later, physical examination revealed a large indurated and ulcerated area with jagged edges at the incision and drainage site (Figure 1). Pyoderma gangrenosum was clinically suspected; a biopsy was performed, and the patient was started on oral prednisone. At 2-week follow-up, the ulcer was found to be rapidly resolving with prednisone and healing with cribriform scarring (Figure 2). Histopathology revealed an undermining neutrophilic inflammatory process that was consistent with PG. A diagnosis of PG was made based on previously published criteria⁷ and the following major/minor criteria in the patient: pathology; absence of infection on histologic analysis; history of pathergy related to worsening ulceration at the site of incision and drainage of the initial boil; clinical findings of an ulcer with peripheral violaceous erythema; undermined borders and tenderness at the site; and rapid resolution of the ulcer with prednisone.

Cessation of adalimumab gradually led to clearance of both psoriasiform lesions and PG; however, HS lesions persisted. At 2-month follow-up, the patient remained clear of new psoriatic and PG lesions. Alternative treatment options for HS, including isotretinoin and other biologic agents, were discussed with the patient. She was subsequently lost to follow-up.

Although the precise pathogenesis of HS is unclear, both genetic abnormalities of the pilosebaceous unit and a dysregulated immune reaction appear to lead to the clinical characteristics of chronic inflammation and scarring seen in HS. A key effector appears to be helper T-cell (T_H17) lymphocyte activation, with increased secretion of TNF-α, IL-1β, and IL-17.^1,2 In turn, IL-17 induces higher expression of TNF-α, leading to a persistent cycle of inflammation. Peripheral recruitment of IL-17–producing neutrophils also may contribute to chronic inflammation.⁸

Adalimumab is the only US Food and Drug Administration–approved biologic indicated for the treatment of HS. Our patient initially responded to adalimumab with improvement of HS; however, treatment had to be discontinued because of the unusual occurrence of 2 distinct paradoxical reactions in a short span of time. Psoriasis and PG are both considered true paradoxical reactions because primary occurrences of both diseases usually are responsive to treatment with adalimumab.

Tumor necrosis factor α inhibitor–induced psoriasis arises de novo and is estimated to occur in approximately 5% of patients with rheumatoid arthritis.^3,6 Palmoplantar pustular psoriasiform reactions are the most common form of paradoxical psoriasis. Topical medications can be used to treat skin lesions, but systemic treatment is required in many cases. Switching to an alternate class of a biologic, such as an IL-17, IL-12/23, or IL-23 inhibitor, can improve the skin reaction; however, such treatment is inconsistently successful, and paradoxical drug reactions also have been seen with these other classes of biologics.^4,9

Recent studies support distinct immune causes for classical and paradoxical psoriasis. In classical psoriasis, plasmacytoid dendritic cells (pDCs) produce IFN-α, which stimulates conventional dendritic cells to produce TNF-α. However, TNF-α matures both pDCs and conventional dendritic cells; upon maturation, both types of dendritic cells lose the ability to produce IFN-α, thus allowing TNF-α to become dominant.¹⁰ The blockade of TNF-α prevents pDC maturation, leading to uninhibited IFN-α, which appears to drive inflammation in paradoxical psoriasis. In classical psoriasis, oligoclonal dermal CD4⁺ T cells and epidermal CD8⁺ T cells remain, even in resolved skin lesions, and can cause disease recurrence through reactivation of skin-resident memory T cells.¹¹ No relapse of paradoxical psoriasis occurs with discontinuation of anti-TNF-α therapy, which supports the notion of an absence of memory T cells.

The incidence of paradoxical psoriasis in patients receiving a TNF-α inhibitor for HS is unclear.¹² There are case series in which patients who had concurrent psoriasis and HS were successfully treated with a TNF-α inhibitor.¹³ A recently recognized condition—PASH syndrome—encompasses the clinical triad of PG, acne, and HS.¹⁰

Our patient had no history of acne or PG, only a long-standing history of HS. New-onset PG occurred only after a TNF-α inhibitor was initiated. Notably, PASH syndrome has been successfully treated with TNF-α inhibitors, highlighting the shared inflammatory etiology of HS and PG.¹⁴ In patients with concurrent PG and HS, TNF-α inhibitors were more effective for treating PG than for HS.

Pyoderma gangrenosum is an inflammatory disorder that often occurs concomitantly with other conditions, such as inflammatory bowel disease. The exact underlying cause of PG is unclear, but there appears to be both neutrophil and T-cell dysfunction in PG, with excess inflammatory cytokine production (eg, IL-1β, TNF-α, IL-17).¹⁵

The mainstay of treatment of PG is systemic corticosteroids and immunosuppressives, such as cyclosporine. Tumor necrosis factor α inhibitors as well as other interleukin inhibitors are increasingly utilized as potential therapeutic alternatives for PG.^16,17

Unlike paradoxical psoriasis, the underlying cause of paradoxical PG is unclear.^18,19 A similar mechanism may be postulated whereby inhibition of TNF-α leads to excessive activation of alternative inflammatory pathways that result in paradoxical PG. In one study, the prevalence of PG among 68,232 patients with HS was 0.18% compared with 0.01% among those without HS; therefore, patients with HS appear to be more predisposed to PG.²⁰

This case illustrates the complex, often conflicting effects of cytokine inhibition in the paradoxical elicitation of alternative inflammatory disorders as an unintended consequence of the initial cytokine blockade. It is likely that genetic predisposition allows for paradoxical reactions in some patients when there is predominant inhibition of one cytokine in the inflammatory pathway. In rare cases, multiple paradoxical reactions are possible.

To the Editor:

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the pilosebaceous unit that occurs in concert with elevations of various cytokines, including tumor necrosis factor α (TNF-α), IL-1β, IL-10, and IL-17.^1,2 Adalimumab is a TNF-α inhibitor approved by the US Food and Drug Administration for the treatment of HS. Although TNF-α inhibitors are effective for many immune-mediated inflammatory disorders, paradoxical drug reactions have been reported following treatment with these agents.^3-6 True paradoxical drug reactions likely are immune mediated and directly lead to new onset of a pathologic condition that would otherwise respond to that drug. For example, there are reports of rheumatoid arthritis patients who were treated with a TNF-α inhibitor and developed psoriatic skin lesions.^3,6 Paradoxical drug reactions also have been reported with acute-onset inflammatory bowel disease and HS or less commonly pyoderma gangrenosum (PG), uveitis, granulomatous reactions, and vasculitis.^4,5 We present the case of a patient with HS who was treated with a TNF-α inhibitor and developed 2 distinct paradoxical drug reactions. We also provide an overview of paradoxical drug reactions associated with TNF-α inhibitors.

A 38-year-old woman developed a painful “boil” on the right leg that was previously treated in the emergency department with incision and drainage as well as oral clindamycin for 7 days, but the lesion spread and continued to worsen. She had a history of HS in the axillae and groin region that had been present since 12 years of age. The condition was poorly controlled despite multiple courses of oral antibiotics and surgical resections. An oral contraceptive also was attempted, but the patient discontinued treatment when liver enzyme levels became elevated. The patient had no other notable medical history, including skin disease. There was a family history of HS in her father and a sibling. Seeking more effective treatment, the patient was offered adalimumab approximately 4 months prior to clinical presentation and agreed to start a course of the drug. She received a loading dose of 160 mg on day 1 and 80 mg on day 15 followed by a maintenance dosage of 40 mg weekly. She experienced improvement in HS symptoms after 3 months on adalimumab; however, she developed scaly pruritic patches on the scalp, arms, and legs that were consistent with psoriasis. Because of the absence of a personal or family history of psoriasis, the patient was informed of the probability of paradoxical psoriasis resulting from adalimumab. She elected to continue adalimumab because of the improvement in HS symptoms, and the psoriatic lesions were mild and adequately controlled with a topical steroid.

At the current presentation 1 month later, physical examination revealed a large indurated and ulcerated area with jagged edges at the incision and drainage site (Figure 1). Pyoderma gangrenosum was clinically suspected; a biopsy was performed, and the patient was started on oral prednisone. At 2-week follow-up, the ulcer was found to be rapidly resolving with prednisone and healing with cribriform scarring (Figure 2). Histopathology revealed an undermining neutrophilic inflammatory process that was consistent with PG. A diagnosis of PG was made based on previously published criteria⁷ and the following major/minor criteria in the patient: pathology; absence of infection on histologic analysis; history of pathergy related to worsening ulceration at the site of incision and drainage of the initial boil; clinical findings of an ulcer with peripheral violaceous erythema; undermined borders and tenderness at the site; and rapid resolution of the ulcer with prednisone.

Cessation of adalimumab gradually led to clearance of both psoriasiform lesions and PG; however, HS lesions persisted. At 2-month follow-up, the patient remained clear of new psoriatic and PG lesions. Alternative treatment options for HS, including isotretinoin and other biologic agents, were discussed with the patient. She was subsequently lost to follow-up.

Although the precise pathogenesis of HS is unclear, both genetic abnormalities of the pilosebaceous unit and a dysregulated immune reaction appear to lead to the clinical characteristics of chronic inflammation and scarring seen in HS. A key effector appears to be helper T-cell (T_H17) lymphocyte activation, with increased secretion of TNF-α, IL-1β, and IL-17.^1,2 In turn, IL-17 induces higher expression of TNF-α, leading to a persistent cycle of inflammation. Peripheral recruitment of IL-17–producing neutrophils also may contribute to chronic inflammation.⁸

Adalimumab is the only US Food and Drug Administration–approved biologic indicated for the treatment of HS. Our patient initially responded to adalimumab with improvement of HS; however, treatment had to be discontinued because of the unusual occurrence of 2 distinct paradoxical reactions in a short span of time. Psoriasis and PG are both considered true paradoxical reactions because primary occurrences of both diseases usually are responsive to treatment with adalimumab.

Tumor necrosis factor α inhibitor–induced psoriasis arises de novo and is estimated to occur in approximately 5% of patients with rheumatoid arthritis.^3,6 Palmoplantar pustular psoriasiform reactions are the most common form of paradoxical psoriasis. Topical medications can be used to treat skin lesions, but systemic treatment is required in many cases. Switching to an alternate class of a biologic, such as an IL-17, IL-12/23, or IL-23 inhibitor, can improve the skin reaction; however, such treatment is inconsistently successful, and paradoxical drug reactions also have been seen with these other classes of biologics.^4,9

Recent studies support distinct immune causes for classical and paradoxical psoriasis. In classical psoriasis, plasmacytoid dendritic cells (pDCs) produce IFN-α, which stimulates conventional dendritic cells to produce TNF-α. However, TNF-α matures both pDCs and conventional dendritic cells; upon maturation, both types of dendritic cells lose the ability to produce IFN-α, thus allowing TNF-α to become dominant.¹⁰ The blockade of TNF-α prevents pDC maturation, leading to uninhibited IFN-α, which appears to drive inflammation in paradoxical psoriasis. In classical psoriasis, oligoclonal dermal CD4⁺ T cells and epidermal CD8⁺ T cells remain, even in resolved skin lesions, and can cause disease recurrence through reactivation of skin-resident memory T cells.¹¹ No relapse of paradoxical psoriasis occurs with discontinuation of anti-TNF-α therapy, which supports the notion of an absence of memory T cells.

The incidence of paradoxical psoriasis in patients receiving a TNF-α inhibitor for HS is unclear.¹² There are case series in which patients who had concurrent psoriasis and HS were successfully treated with a TNF-α inhibitor.¹³ A recently recognized condition—PASH syndrome—encompasses the clinical triad of PG, acne, and HS.¹⁰

Our patient had no history of acne or PG, only a long-standing history of HS. New-onset PG occurred only after a TNF-α inhibitor was initiated. Notably, PASH syndrome has been successfully treated with TNF-α inhibitors, highlighting the shared inflammatory etiology of HS and PG.¹⁴ In patients with concurrent PG and HS, TNF-α inhibitors were more effective for treating PG than for HS.

Pyoderma gangrenosum is an inflammatory disorder that often occurs concomitantly with other conditions, such as inflammatory bowel disease. The exact underlying cause of PG is unclear, but there appears to be both neutrophil and T-cell dysfunction in PG, with excess inflammatory cytokine production (eg, IL-1β, TNF-α, IL-17).¹⁵

The mainstay of treatment of PG is systemic corticosteroids and immunosuppressives, such as cyclosporine. Tumor necrosis factor α inhibitors as well as other interleukin inhibitors are increasingly utilized as potential therapeutic alternatives for PG.^16,17

Unlike paradoxical psoriasis, the underlying cause of paradoxical PG is unclear.^18,19 A similar mechanism may be postulated whereby inhibition of TNF-α leads to excessive activation of alternative inflammatory pathways that result in paradoxical PG. In one study, the prevalence of PG among 68,232 patients with HS was 0.18% compared with 0.01% among those without HS; therefore, patients with HS appear to be more predisposed to PG.²⁰

This case illustrates the complex, often conflicting effects of cytokine inhibition in the paradoxical elicitation of alternative inflammatory disorders as an unintended consequence of the initial cytokine blockade. It is likely that genetic predisposition allows for paradoxical reactions in some patients when there is predominant inhibition of one cytokine in the inflammatory pathway. In rare cases, multiple paradoxical reactions are possible.

To the Editor:

Many types of neoplasms can show aberrant immunoreactivity or unexpected expression of markers.¹ Malignant melanoma is a tumor that can show not only aberrant immunohistochemical staining patterns but also notable histologic diversity,^1,2 which often makes the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.²

The incidence of malignant melanoma continues to grow.³ Maintaining a high degree of suspicion for this disease, recognizing its heterogeneity and divergent differentiation, and knowing potential aberrant immunohistochemical staining patterns are imperative for accurate diagnosis.

A 36-year-old man presented to a primary care physician with right-sided chest pain, upper and lower back aches, bilateral hip pain, neck pain, headache, night sweats, chills, and nausea. After infectious causes were ruled out, he was placed on a steroid taper without improvement. He presented to the emergency department a few days later with muscle spasms and was found to also have diffuse abdominal tenderness and guarding. The patient’s medical history was noncontributory; he was a lifelong nonsmoker. Laboratory studies revealed elevated levels of alanine aminotransferase and C-reactive protein. Computed tomography of the chest and abdomen revealed innumerable liver and lung lesions that were suspicious for metastatic malignancy. A liver biopsy revealed nests and sheets of metastatic tumor with pleomorphic nuclei, inconspicuous nucleoli, and areas of intranuclear clearing (Figures 1 and 2). Immunohistochemical staining was performed to further characterize the tumor. Neoplastic cells were positive for MART-1 (also known as Melan-A and melanoma-associated antigen recognized by T cells)(Figure 3), SOX10, S-100, HMB-45, and vimentin. Nonspecific staining with CD56 (Figure 4), a neuroendocrine marker, also was noted; however, the neoplasm was negative for synaptophysin, another neuroendocrine marker. Other markers for which staining was negative included pan-keratin, CD138 (syndecan-1), desmin, placental alkaline phosphatase (PLAP), inhibin, OCT-4, cytokeratin 7, and cytokeratin 20. This staining pattern was compatible with metastatic melanoma with aberrant CD56 expression.

BRAF V600E immunohistochemical staining also was performed and showed strong and diffuse positivity within neoplastic cells. A subsequent positron emission tomography scan revealed widespread metastatic disease involving the lungs, liver, spleen, and bones. The patient did not have a history of an excised skin lesion; no primary cutaneous or mucosal lesions were identified.

The patient was started on targeted therapy with trametinib, a mitogen-activated extracellular signal-related kinase kinase (MEK) inhibitor, and dabrafenib, a BRAF inhibitor. The disease continued to progress; he developed extensive leptomeningeal metastatic disease for which palliative radiation therapy was administered. The patient died 4 months after the initial diagnosis.

More than 90% of melanoma cases are of cutaneous origin; however, 4% to 8% of cases present as a metastatic lesion in the absence of an identified primary lesion,⁴ similar to our patient. The diagnosis of melanoma often is challenging; the tumor can show notable histologic diversity and has the potential to express aberrant immunophenotypes.^1,2 The histologic diversity of melanoma includes a variety of architectural patterns (eg, nests, trabeculae, fascicular, pseudoglandular, pseudopapillary, or pseudorosette patterns), cytomorphologic features, and stromal changes. Cytomorphologic features of melanoma can be large pleomorphic cells; small cells; spindle cells; clear cells; signet-ring cells; and rhabdoid, plasmacytoid, and balloon cells.⁵

Melanoma can mimic carcinoma, sarcoma, lymphoma, benign stromal tumors, plasmacytoma, and germ-cell tumors.⁵ Nuclei can binucleated, multinucleated, or lobated and may contain inclusions or grooves. Stroma may become myxoid or desmoplastic in appearance or rarely show granulomatous inflammation or osteoclastic giant cells.⁵ These variations render the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.

Melanomas typically express MART-1, HMB-45, S-100, tyrosinase, NK1C3, vimentin, and neuron-specific enolase. However, melanoma is among the many neoplasms that sometimes exhibit aberrant immunoreactivity and differentiation toward nonmelanocytic elements.⁶ The most commonly expressed immunophenotypic aberration is cytokeratin, especially the low-molecular-weight keratin marker CAM5.2.⁵ CAM5.2 positivity also is seen more often in metastatic melanoma. Melanomas rarely express other intermediate filaments, including desmin, neurofilament protein, and glial fibrillary acidic protein; expression of smooth-muscle actin is rare.⁵

Only a few cases of melanoma showing expression of neuroendocrine markers have been reported. However, one study reported synaptophysin positivity in 29% (10/34) of cases of primary and metastatic melanoma, making the stain a relatively common finding.¹

In contrast, expression of CD56 (also known as neural-cell adhesion molecule 1) in melanoma has been reported only rarely. CD56 is a nonspecific neuroendocrine marker that normally is expressed on neurons, glial tissue, skeletal muscle, and natural killer cells. Riddle and Bui⁷ reported a case of metastatic malignant melanoma with focal CD56 positivity and no expression of other neuroendocrine markers, similar to our patient. Suzuki and colleagues⁴ also reported a case of melanoma metastatic to bone marrow that showed CD56 expression in true nonhematologic tumor cells and negative immunoreactivity with synaptophysin and chromogranin A.

It is important to document cases of melanoma that express neuroendocrine markers to prevent an incorrect diagnosis of a neuroendocrine tumor.¹ In some cases, distinguishing amelanotic melanoma from poorly differentiated squamous cell carcinoma, neuroendocrine tumor, and lymphoma can be difficult.⁵

The term neuroendocrine differentiation is reserved for cases of melanoma that show areas of ultrastructural change consistent with a neuroendocrine tumor.² Neuroendocrine differentiation in melanoma is not common; its prognostic significance is unknown.⁸ We do not consider our case to be true neuroendocrine differentiation, as the tumor lacked the morphologic changes of a neuroendocrine tumor. Furthermore, CD56 is a nonspecific neuroendocrine marker, and the tumor was negative for synaptophysin.

Melanoma has the potential to show notable histologic diversity as well as aberrant immunohistochemical staining patterns.^1,2 Our patient had metastatic melanoma with aberrant neuroendocrine expression of CD56, which could have been a potential diagnostic pitfall. Because expression of CD56 in melanoma is rare, it is imperative to recognize this potential aberrant staining pattern to ensure the accurate diagnosis of melanoma and appropriate provision of care.

To the Editor:

Many types of neoplasms can show aberrant immunoreactivity or unexpected expression of markers.¹ Malignant melanoma is a tumor that can show not only aberrant immunohistochemical staining patterns but also notable histologic diversity,^1,2 which often makes the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.²

The incidence of malignant melanoma continues to grow.³ Maintaining a high degree of suspicion for this disease, recognizing its heterogeneity and divergent differentiation, and knowing potential aberrant immunohistochemical staining patterns are imperative for accurate diagnosis.

A 36-year-old man presented to a primary care physician with right-sided chest pain, upper and lower back aches, bilateral hip pain, neck pain, headache, night sweats, chills, and nausea. After infectious causes were ruled out, he was placed on a steroid taper without improvement. He presented to the emergency department a few days later with muscle spasms and was found to also have diffuse abdominal tenderness and guarding. The patient’s medical history was noncontributory; he was a lifelong nonsmoker. Laboratory studies revealed elevated levels of alanine aminotransferase and C-reactive protein. Computed tomography of the chest and abdomen revealed innumerable liver and lung lesions that were suspicious for metastatic malignancy. A liver biopsy revealed nests and sheets of metastatic tumor with pleomorphic nuclei, inconspicuous nucleoli, and areas of intranuclear clearing (Figures 1 and 2). Immunohistochemical staining was performed to further characterize the tumor. Neoplastic cells were positive for MART-1 (also known as Melan-A and melanoma-associated antigen recognized by T cells)(Figure 3), SOX10, S-100, HMB-45, and vimentin. Nonspecific staining with CD56 (Figure 4), a neuroendocrine marker, also was noted; however, the neoplasm was negative for synaptophysin, another neuroendocrine marker. Other markers for which staining was negative included pan-keratin, CD138 (syndecan-1), desmin, placental alkaline phosphatase (PLAP), inhibin, OCT-4, cytokeratin 7, and cytokeratin 20. This staining pattern was compatible with metastatic melanoma with aberrant CD56 expression.

BRAF V600E immunohistochemical staining also was performed and showed strong and diffuse positivity within neoplastic cells. A subsequent positron emission tomography scan revealed widespread metastatic disease involving the lungs, liver, spleen, and bones. The patient did not have a history of an excised skin lesion; no primary cutaneous or mucosal lesions were identified.

The patient was started on targeted therapy with trametinib, a mitogen-activated extracellular signal-related kinase kinase (MEK) inhibitor, and dabrafenib, a BRAF inhibitor. The disease continued to progress; he developed extensive leptomeningeal metastatic disease for which palliative radiation therapy was administered. The patient died 4 months after the initial diagnosis.

More than 90% of melanoma cases are of cutaneous origin; however, 4% to 8% of cases present as a metastatic lesion in the absence of an identified primary lesion,⁴ similar to our patient. The diagnosis of melanoma often is challenging; the tumor can show notable histologic diversity and has the potential to express aberrant immunophenotypes.^1,2 The histologic diversity of melanoma includes a variety of architectural patterns (eg, nests, trabeculae, fascicular, pseudoglandular, pseudopapillary, or pseudorosette patterns), cytomorphologic features, and stromal changes. Cytomorphologic features of melanoma can be large pleomorphic cells; small cells; spindle cells; clear cells; signet-ring cells; and rhabdoid, plasmacytoid, and balloon cells.⁵

Melanoma can mimic carcinoma, sarcoma, lymphoma, benign stromal tumors, plasmacytoma, and germ-cell tumors.⁵ Nuclei can binucleated, multinucleated, or lobated and may contain inclusions or grooves. Stroma may become myxoid or desmoplastic in appearance or rarely show granulomatous inflammation or osteoclastic giant cells.⁵ These variations render the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.

Melanomas typically express MART-1, HMB-45, S-100, tyrosinase, NK1C3, vimentin, and neuron-specific enolase. However, melanoma is among the many neoplasms that sometimes exhibit aberrant immunoreactivity and differentiation toward nonmelanocytic elements.⁶ The most commonly expressed immunophenotypic aberration is cytokeratin, especially the low-molecular-weight keratin marker CAM5.2.⁵ CAM5.2 positivity also is seen more often in metastatic melanoma. Melanomas rarely express other intermediate filaments, including desmin, neurofilament protein, and glial fibrillary acidic protein; expression of smooth-muscle actin is rare.⁵

Only a few cases of melanoma showing expression of neuroendocrine markers have been reported. However, one study reported synaptophysin positivity in 29% (10/34) of cases of primary and metastatic melanoma, making the stain a relatively common finding.¹

In contrast, expression of CD56 (also known as neural-cell adhesion molecule 1) in melanoma has been reported only rarely. CD56 is a nonspecific neuroendocrine marker that normally is expressed on neurons, glial tissue, skeletal muscle, and natural killer cells. Riddle and Bui⁷ reported a case of metastatic malignant melanoma with focal CD56 positivity and no expression of other neuroendocrine markers, similar to our patient. Suzuki and colleagues⁴ also reported a case of melanoma metastatic to bone marrow that showed CD56 expression in true nonhematologic tumor cells and negative immunoreactivity with synaptophysin and chromogranin A.

It is important to document cases of melanoma that express neuroendocrine markers to prevent an incorrect diagnosis of a neuroendocrine tumor.¹ In some cases, distinguishing amelanotic melanoma from poorly differentiated squamous cell carcinoma, neuroendocrine tumor, and lymphoma can be difficult.⁵

The term neuroendocrine differentiation is reserved for cases of melanoma that show areas of ultrastructural change consistent with a neuroendocrine tumor.² Neuroendocrine differentiation in melanoma is not common; its prognostic significance is unknown.⁸ We do not consider our case to be true neuroendocrine differentiation, as the tumor lacked the morphologic changes of a neuroendocrine tumor. Furthermore, CD56 is a nonspecific neuroendocrine marker, and the tumor was negative for synaptophysin.

Melanoma has the potential to show notable histologic diversity as well as aberrant immunohistochemical staining patterns.^1,2 Our patient had metastatic melanoma with aberrant neuroendocrine expression of CD56, which could have been a potential diagnostic pitfall. Because expression of CD56 in melanoma is rare, it is imperative to recognize this potential aberrant staining pattern to ensure the accurate diagnosis of melanoma and appropriate provision of care.

To the Editor:

Many types of neoplasms can show aberrant immunoreactivity or unexpected expression of markers.¹ Malignant melanoma is a tumor that can show not only aberrant immunohistochemical staining patterns but also notable histologic diversity,^1,2 which often makes the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.²

The incidence of malignant melanoma continues to grow.³ Maintaining a high degree of suspicion for this disease, recognizing its heterogeneity and divergent differentiation, and knowing potential aberrant immunohistochemical staining patterns are imperative for accurate diagnosis.

A 36-year-old man presented to a primary care physician with right-sided chest pain, upper and lower back aches, bilateral hip pain, neck pain, headache, night sweats, chills, and nausea. After infectious causes were ruled out, he was placed on a steroid taper without improvement. He presented to the emergency department a few days later with muscle spasms and was found to also have diffuse abdominal tenderness and guarding. The patient’s medical history was noncontributory; he was a lifelong nonsmoker. Laboratory studies revealed elevated levels of alanine aminotransferase and C-reactive protein. Computed tomography of the chest and abdomen revealed innumerable liver and lung lesions that were suspicious for metastatic malignancy. A liver biopsy revealed nests and sheets of metastatic tumor with pleomorphic nuclei, inconspicuous nucleoli, and areas of intranuclear clearing (Figures 1 and 2). Immunohistochemical staining was performed to further characterize the tumor. Neoplastic cells were positive for MART-1 (also known as Melan-A and melanoma-associated antigen recognized by T cells)(Figure 3), SOX10, S-100, HMB-45, and vimentin. Nonspecific staining with CD56 (Figure 4), a neuroendocrine marker, also was noted; however, the neoplasm was negative for synaptophysin, another neuroendocrine marker. Other markers for which staining was negative included pan-keratin, CD138 (syndecan-1), desmin, placental alkaline phosphatase (PLAP), inhibin, OCT-4, cytokeratin 7, and cytokeratin 20. This staining pattern was compatible with metastatic melanoma with aberrant CD56 expression.

BRAF V600E immunohistochemical staining also was performed and showed strong and diffuse positivity within neoplastic cells. A subsequent positron emission tomography scan revealed widespread metastatic disease involving the lungs, liver, spleen, and bones. The patient did not have a history of an excised skin lesion; no primary cutaneous or mucosal lesions were identified.

The patient was started on targeted therapy with trametinib, a mitogen-activated extracellular signal-related kinase kinase (MEK) inhibitor, and dabrafenib, a BRAF inhibitor. The disease continued to progress; he developed extensive leptomeningeal metastatic disease for which palliative radiation therapy was administered. The patient died 4 months after the initial diagnosis.

More than 90% of melanoma cases are of cutaneous origin; however, 4% to 8% of cases present as a metastatic lesion in the absence of an identified primary lesion,⁴ similar to our patient. The diagnosis of melanoma often is challenging; the tumor can show notable histologic diversity and has the potential to express aberrant immunophenotypes.^1,2 The histologic diversity of melanoma includes a variety of architectural patterns (eg, nests, trabeculae, fascicular, pseudoglandular, pseudopapillary, or pseudorosette patterns), cytomorphologic features, and stromal changes. Cytomorphologic features of melanoma can be large pleomorphic cells; small cells; spindle cells; clear cells; signet-ring cells; and rhabdoid, plasmacytoid, and balloon cells.⁵

Melanoma can mimic carcinoma, sarcoma, lymphoma, benign stromal tumors, plasmacytoma, and germ-cell tumors.⁵ Nuclei can binucleated, multinucleated, or lobated and may contain inclusions or grooves. Stroma may become myxoid or desmoplastic in appearance or rarely show granulomatous inflammation or osteoclastic giant cells.⁵ These variations render the diagnosis of melanoma challenging and ultimately can lead to diagnostic uncertainty.

Melanomas typically express MART-1, HMB-45, S-100, tyrosinase, NK1C3, vimentin, and neuron-specific enolase. However, melanoma is among the many neoplasms that sometimes exhibit aberrant immunoreactivity and differentiation toward nonmelanocytic elements.⁶ The most commonly expressed immunophenotypic aberration is cytokeratin, especially the low-molecular-weight keratin marker CAM5.2.⁵ CAM5.2 positivity also is seen more often in metastatic melanoma. Melanomas rarely express other intermediate filaments, including desmin, neurofilament protein, and glial fibrillary acidic protein; expression of smooth-muscle actin is rare.⁵

Only a few cases of melanoma showing expression of neuroendocrine markers have been reported. However, one study reported synaptophysin positivity in 29% (10/34) of cases of primary and metastatic melanoma, making the stain a relatively common finding.¹

In contrast, expression of CD56 (also known as neural-cell adhesion molecule 1) in melanoma has been reported only rarely. CD56 is a nonspecific neuroendocrine marker that normally is expressed on neurons, glial tissue, skeletal muscle, and natural killer cells. Riddle and Bui⁷ reported a case of metastatic malignant melanoma with focal CD56 positivity and no expression of other neuroendocrine markers, similar to our patient. Suzuki and colleagues⁴ also reported a case of melanoma metastatic to bone marrow that showed CD56 expression in true nonhematologic tumor cells and negative immunoreactivity with synaptophysin and chromogranin A.

It is important to document cases of melanoma that express neuroendocrine markers to prevent an incorrect diagnosis of a neuroendocrine tumor.¹ In some cases, distinguishing amelanotic melanoma from poorly differentiated squamous cell carcinoma, neuroendocrine tumor, and lymphoma can be difficult.⁵

The term neuroendocrine differentiation is reserved for cases of melanoma that show areas of ultrastructural change consistent with a neuroendocrine tumor.² Neuroendocrine differentiation in melanoma is not common; its prognostic significance is unknown.⁸ We do not consider our case to be true neuroendocrine differentiation, as the tumor lacked the morphologic changes of a neuroendocrine tumor. Furthermore, CD56 is a nonspecific neuroendocrine marker, and the tumor was negative for synaptophysin.

Melanoma has the potential to show notable histologic diversity as well as aberrant immunohistochemical staining patterns.^1,2 Our patient had metastatic melanoma with aberrant neuroendocrine expression of CD56, which could have been a potential diagnostic pitfall. Because expression of CD56 in melanoma is rare, it is imperative to recognize this potential aberrant staining pattern to ensure the accurate diagnosis of melanoma and appropriate provision of care.

To the Editor:

Cutaneous collagenous vasculopathy (CCV) is an uncommon microangiopathy that presents with progressive telangiectases on the lower extremities that can eventually spread to involve the upper extremities and trunk. Systemic involvement is uncommon. The diagnosis is confirmed by biopsy, which demonstrates dilated capillaries and postcapillary venules with eosinophilic hyalinized walls. Treatment generally has focused on the use of vascular lasers.¹ We report a patient with advanced CCV and ocular involvement that responded to a combination of pulsed dye laser (PDL) therapy and sclerotherapy for cutaneous lesions.

A 63-year-old woman presented with partially blanchable, purple-black patches on the lower extremities (Figure 1). The upper extremities had minimal involvement at the time of presentation. A medical history revealed the lesions presented on the legs 10 years prior but were beginning to form on the arms. She had a history of hypertension and bleeding in the retina.

Histopathology revealed prominent dilation of postcapillary venules with eosinophilic collagenous materials in the vessel walls that was positive on periodic acid–Schiff stain, confirming the diagnosis of CCV. The perivascular collagenous material failed to stain with Congo red. Laboratory testing for serum protein electrophoresis, antinuclear antibodies, and baseline hematologic and metabolic panels revealed no abnormalities.

Over 3 years of treatment with PDL, most of the black patches resolved, but prominent telangiectatic vessels remained (Figure 2). Sclerotherapy with polidocanol (10 mg/mL) resulted in clearance of the majority of telangiectatic vessels. After each sclerotherapy treatment, Unna boots were applied for a minimum of 24 hours. The patient had no adverse effects from either PDL or sclerotherapy and was pleased with the results (Figure 3). An ophthalmologist had attributed the retinal bleeding to central serous chorioretinopathy, but tortuosity of superficial scleral and episcleral vessels progressed, suggesting CCV as the more likely cause (Figure 4). Currently, she is being followed for visual changes and further retinal bleeding.

Early CCV typically appears as blanchable pink or red macules, telangiectases, or petechiae on the lower extremities, progressing to involve the trunk and upper extremity.^1-3 In rare cases, CCV presents in a papular or annular variant instead of the typical telangiectatic form.^4,5 As the lesions progress, they often darken in appearance. Bleeding can occur, and the progressive patches are disfiguring.^6,7 Middle-aged to older adults typically present with CCV (range, 16–83 years), with a mean age of 62 years.^1,2,6 This disease affects both males and females, predominantly in White individuals.¹ Extracutaneous manifestations are rare.^1,2,6 One case of mucosal involvement was described in a patient with glossitis and oral erosions.⁸ We found no prior reports of nail or eye changes.^1,2

The etiology of CCV is unknown, but different theories have been proposed. One is that CCV is due to a genetic defect that changes collagen synthesis in the cutaneous microvasculature. Another more widely held belief is that CCV originates from an injury that occurs to the microvasculature endothelial cells. Regardless of the cause of the triggering injury, the result is induced intravascular occlusive microthrombi that cause perivascular fibrosis and endothelial hyperplasia.^2,6,7,9

Cutaneous collagenous vasculopathy may be influenced by systemic diseases. The most common comorbidities are hypertension, cardiovascular disease, diabetes mellitus, and hyperlipidemia.^1,3,6-8 The presentation of CCV with a malignancy is rare; 1 patient was diagnosed with multiple myeloma 18 months after CCV, and another patient’s cutaneous presentation led to discovery of pancreatic cancer with metastasis.^8,10 In this setting, the increased growth factors or hypercoagulability of malignancy may play a role in endothelial cell damage and hyperplasia. Autoimmune vascular injury also has been suggested to trigger CCV; 1 case involved antiribonucleoprotein antibodies, while another case involved anti–endothelial cell antibody assays.¹¹ In addition, CCV has been reported in hypercoagulable patients, demonstrating another route for endothelial damage, with 1 patient being heterozygous for prothrombin G20210A, a report of CCV in a patient with cryofibrinogenemia, and another patient being found positive for lupus anticoagulant.^11,12 Drugs also have been thought to influence CCV, including corticosteroids, lithium, thiothixene, interferon, isotretinoin, calcium channel blockers, antibiotics, hydroxyurea, and antidepressants.^7,11

The diagnosis of CCV is confirmed using light microscopy and collagen-specific immunostaining. Examination shows hyaline eosinophilic deposition of type IV collagen around the affected vessels, with the postcapillary venules showing characteristic duplication of the basal lamina.^3,9 The material stains positive with periodic acid-Schiff and Masson trichrome.³

Underreporting may contribute to the low incidence of CCV. The clinical presentation of CCV is similar to generalized essential telangiectasia, with biopsy distinguishing the two. Other diagnoses in the differential include hereditary hemorrhagic telangiectasia, which typically would have mucosal involvement; radiating telangiectatic mats and a strong family history; and hereditary benign telangiectasia, which typically presents in younger patients aged 1 year to adolescence.¹

Treatment with vascular lasers has been the main focus, using either the 595-nm PDL or the 1064-nm Nd:YAG laser.^6,13 Pulsed dye laser or intense pulsed light devices can improve patient well-being^1,2; intense pulsed light allows for a larger spot size and may be preferred in patients with a larger body surface area involved.¹³ However, a few other treatments have been proposed. One case report noted poor response to sclerotherapy.¹ In another case, a patient treated with a chemotherapy agent, bortezomib, for their concurrent multiple myeloma showed notable CCV cutaneous improvement. The proposed mechanism for bortezomib improving CCV is through its antiproliferative effect on endothelial cells of the superficial dermal vessels.⁸ Our patient did not achieve an adequate response with PDL, but the addition of sclerotherapy with polidocanol induced a successful response.

Patients should be examined for evidence of ocular involvement and referred to an ophthalmologist for appropriate care. Although there is no definite association with systemic illnesses or mediation, recent associations with an autoimmune disorder or underlying malignancy have been noted.^8,10,11 Age-appropriate cancer screening and attention to associated signs and symptoms are recommended.

To the Editor:

Cutaneous collagenous vasculopathy (CCV) is an uncommon microangiopathy that presents with progressive telangiectases on the lower extremities that can eventually spread to involve the upper extremities and trunk. Systemic involvement is uncommon. The diagnosis is confirmed by biopsy, which demonstrates dilated capillaries and postcapillary venules with eosinophilic hyalinized walls. Treatment generally has focused on the use of vascular lasers.¹ We report a patient with advanced CCV and ocular involvement that responded to a combination of pulsed dye laser (PDL) therapy and sclerotherapy for cutaneous lesions.

A 63-year-old woman presented with partially blanchable, purple-black patches on the lower extremities (Figure 1). The upper extremities had minimal involvement at the time of presentation. A medical history revealed the lesions presented on the legs 10 years prior but were beginning to form on the arms. She had a history of hypertension and bleeding in the retina.

Histopathology revealed prominent dilation of postcapillary venules with eosinophilic collagenous materials in the vessel walls that was positive on periodic acid–Schiff stain, confirming the diagnosis of CCV. The perivascular collagenous material failed to stain with Congo red. Laboratory testing for serum protein electrophoresis, antinuclear antibodies, and baseline hematologic and metabolic panels revealed no abnormalities.

Over 3 years of treatment with PDL, most of the black patches resolved, but prominent telangiectatic vessels remained (Figure 2). Sclerotherapy with polidocanol (10 mg/mL) resulted in clearance of the majority of telangiectatic vessels. After each sclerotherapy treatment, Unna boots were applied for a minimum of 24 hours. The patient had no adverse effects from either PDL or sclerotherapy and was pleased with the results (Figure 3). An ophthalmologist had attributed the retinal bleeding to central serous chorioretinopathy, but tortuosity of superficial scleral and episcleral vessels progressed, suggesting CCV as the more likely cause (Figure 4). Currently, she is being followed for visual changes and further retinal bleeding.

Early CCV typically appears as blanchable pink or red macules, telangiectases, or petechiae on the lower extremities, progressing to involve the trunk and upper extremity.^1-3 In rare cases, CCV presents in a papular or annular variant instead of the typical telangiectatic form.^4,5 As the lesions progress, they often darken in appearance. Bleeding can occur, and the progressive patches are disfiguring.^6,7 Middle-aged to older adults typically present with CCV (range, 16–83 years), with a mean age of 62 years.^1,2,6 This disease affects both males and females, predominantly in White individuals.¹ Extracutaneous manifestations are rare.^1,2,6 One case of mucosal involvement was described in a patient with glossitis and oral erosions.⁸ We found no prior reports of nail or eye changes.^1,2

The etiology of CCV is unknown, but different theories have been proposed. One is that CCV is due to a genetic defect that changes collagen synthesis in the cutaneous microvasculature. Another more widely held belief is that CCV originates from an injury that occurs to the microvasculature endothelial cells. Regardless of the cause of the triggering injury, the result is induced intravascular occlusive microthrombi that cause perivascular fibrosis and endothelial hyperplasia.^2,6,7,9

Cutaneous collagenous vasculopathy may be influenced by systemic diseases. The most common comorbidities are hypertension, cardiovascular disease, diabetes mellitus, and hyperlipidemia.^1,3,6-8 The presentation of CCV with a malignancy is rare; 1 patient was diagnosed with multiple myeloma 18 months after CCV, and another patient’s cutaneous presentation led to discovery of pancreatic cancer with metastasis.^8,10 In this setting, the increased growth factors or hypercoagulability of malignancy may play a role in endothelial cell damage and hyperplasia. Autoimmune vascular injury also has been suggested to trigger CCV; 1 case involved antiribonucleoprotein antibodies, while another case involved anti–endothelial cell antibody assays.¹¹ In addition, CCV has been reported in hypercoagulable patients, demonstrating another route for endothelial damage, with 1 patient being heterozygous for prothrombin G20210A, a report of CCV in a patient with cryofibrinogenemia, and another patient being found positive for lupus anticoagulant.^11,12 Drugs also have been thought to influence CCV, including corticosteroids, lithium, thiothixene, interferon, isotretinoin, calcium channel blockers, antibiotics, hydroxyurea, and antidepressants.^7,11

The diagnosis of CCV is confirmed using light microscopy and collagen-specific immunostaining. Examination shows hyaline eosinophilic deposition of type IV collagen around the affected vessels, with the postcapillary venules showing characteristic duplication of the basal lamina.^3,9 The material stains positive with periodic acid-Schiff and Masson trichrome.³

Underreporting may contribute to the low incidence of CCV. The clinical presentation of CCV is similar to generalized essential telangiectasia, with biopsy distinguishing the two. Other diagnoses in the differential include hereditary hemorrhagic telangiectasia, which typically would have mucosal involvement; radiating telangiectatic mats and a strong family history; and hereditary benign telangiectasia, which typically presents in younger patients aged 1 year to adolescence.¹

Treatment with vascular lasers has been the main focus, using either the 595-nm PDL or the 1064-nm Nd:YAG laser.^6,13 Pulsed dye laser or intense pulsed light devices can improve patient well-being^1,2; intense pulsed light allows for a larger spot size and may be preferred in patients with a larger body surface area involved.¹³ However, a few other treatments have been proposed. One case report noted poor response to sclerotherapy.¹ In another case, a patient treated with a chemotherapy agent, bortezomib, for their concurrent multiple myeloma showed notable CCV cutaneous improvement. The proposed mechanism for bortezomib improving CCV is through its antiproliferative effect on endothelial cells of the superficial dermal vessels.⁸ Our patient did not achieve an adequate response with PDL, but the addition of sclerotherapy with polidocanol induced a successful response.

Patients should be examined for evidence of ocular involvement and referred to an ophthalmologist for appropriate care. Although there is no definite association with systemic illnesses or mediation, recent associations with an autoimmune disorder or underlying malignancy have been noted.^8,10,11 Age-appropriate cancer screening and attention to associated signs and symptoms are recommended.

To the Editor:

Cutaneous collagenous vasculopathy (CCV) is an uncommon microangiopathy that presents with progressive telangiectases on the lower extremities that can eventually spread to involve the upper extremities and trunk. Systemic involvement is uncommon. The diagnosis is confirmed by biopsy, which demonstrates dilated capillaries and postcapillary venules with eosinophilic hyalinized walls. Treatment generally has focused on the use of vascular lasers.¹ We report a patient with advanced CCV and ocular involvement that responded to a combination of pulsed dye laser (PDL) therapy and sclerotherapy for cutaneous lesions.

A 63-year-old woman presented with partially blanchable, purple-black patches on the lower extremities (Figure 1). The upper extremities had minimal involvement at the time of presentation. A medical history revealed the lesions presented on the legs 10 years prior but were beginning to form on the arms. She had a history of hypertension and bleeding in the retina.

Histopathology revealed prominent dilation of postcapillary venules with eosinophilic collagenous materials in the vessel walls that was positive on periodic acid–Schiff stain, confirming the diagnosis of CCV. The perivascular collagenous material failed to stain with Congo red. Laboratory testing for serum protein electrophoresis, antinuclear antibodies, and baseline hematologic and metabolic panels revealed no abnormalities.

Over 3 years of treatment with PDL, most of the black patches resolved, but prominent telangiectatic vessels remained (Figure 2). Sclerotherapy with polidocanol (10 mg/mL) resulted in clearance of the majority of telangiectatic vessels. After each sclerotherapy treatment, Unna boots were applied for a minimum of 24 hours. The patient had no adverse effects from either PDL or sclerotherapy and was pleased with the results (Figure 3). An ophthalmologist had attributed the retinal bleeding to central serous chorioretinopathy, but tortuosity of superficial scleral and episcleral vessels progressed, suggesting CCV as the more likely cause (Figure 4). Currently, she is being followed for visual changes and further retinal bleeding.

Early CCV typically appears as blanchable pink or red macules, telangiectases, or petechiae on the lower extremities, progressing to involve the trunk and upper extremity.^1-3 In rare cases, CCV presents in a papular or annular variant instead of the typical telangiectatic form.^4,5 As the lesions progress, they often darken in appearance. Bleeding can occur, and the progressive patches are disfiguring.^6,7 Middle-aged to older adults typically present with CCV (range, 16–83 years), with a mean age of 62 years.^1,2,6 This disease affects both males and females, predominantly in White individuals.¹ Extracutaneous manifestations are rare.^1,2,6 One case of mucosal involvement was described in a patient with glossitis and oral erosions.⁸ We found no prior reports of nail or eye changes.^1,2

The etiology of CCV is unknown, but different theories have been proposed. One is that CCV is due to a genetic defect that changes collagen synthesis in the cutaneous microvasculature. Another more widely held belief is that CCV originates from an injury that occurs to the microvasculature endothelial cells. Regardless of the cause of the triggering injury, the result is induced intravascular occlusive microthrombi that cause perivascular fibrosis and endothelial hyperplasia.^2,6,7,9

Cutaneous collagenous vasculopathy may be influenced by systemic diseases. The most common comorbidities are hypertension, cardiovascular disease, diabetes mellitus, and hyperlipidemia.^1,3,6-8 The presentation of CCV with a malignancy is rare; 1 patient was diagnosed with multiple myeloma 18 months after CCV, and another patient’s cutaneous presentation led to discovery of pancreatic cancer with metastasis.^8,10 In this setting, the increased growth factors or hypercoagulability of malignancy may play a role in endothelial cell damage and hyperplasia. Autoimmune vascular injury also has been suggested to trigger CCV; 1 case involved antiribonucleoprotein antibodies, while another case involved anti–endothelial cell antibody assays.¹¹ In addition, CCV has been reported in hypercoagulable patients, demonstrating another route for endothelial damage, with 1 patient being heterozygous for prothrombin G20210A, a report of CCV in a patient with cryofibrinogenemia, and another patient being found positive for lupus anticoagulant.^11,12 Drugs also have been thought to influence CCV, including corticosteroids, lithium, thiothixene, interferon, isotretinoin, calcium channel blockers, antibiotics, hydroxyurea, and antidepressants.^7,11

The diagnosis of CCV is confirmed using light microscopy and collagen-specific immunostaining. Examination shows hyaline eosinophilic deposition of type IV collagen around the affected vessels, with the postcapillary venules showing characteristic duplication of the basal lamina.^3,9 The material stains positive with periodic acid-Schiff and Masson trichrome.³

Underreporting may contribute to the low incidence of CCV. The clinical presentation of CCV is similar to generalized essential telangiectasia, with biopsy distinguishing the two. Other diagnoses in the differential include hereditary hemorrhagic telangiectasia, which typically would have mucosal involvement; radiating telangiectatic mats and a strong family history; and hereditary benign telangiectasia, which typically presents in younger patients aged 1 year to adolescence.¹

Treatment with vascular lasers has been the main focus, using either the 595-nm PDL or the 1064-nm Nd:YAG laser.^6,13 Pulsed dye laser or intense pulsed light devices can improve patient well-being^1,2; intense pulsed light allows for a larger spot size and may be preferred in patients with a larger body surface area involved.¹³ However, a few other treatments have been proposed. One case report noted poor response to sclerotherapy.¹ In another case, a patient treated with a chemotherapy agent, bortezomib, for their concurrent multiple myeloma showed notable CCV cutaneous improvement. The proposed mechanism for bortezomib improving CCV is through its antiproliferative effect on endothelial cells of the superficial dermal vessels.⁸ Our patient did not achieve an adequate response with PDL, but the addition of sclerotherapy with polidocanol induced a successful response.

Patients should be examined for evidence of ocular involvement and referred to an ophthalmologist for appropriate care. Although there is no definite association with systemic illnesses or mediation, recent associations with an autoimmune disorder or underlying malignancy have been noted.^8,10,11 Age-appropriate cancer screening and attention to associated signs and symptoms are recommended.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

To the Editor:

A 16-year-old adolescent boy presented to our pediatric dermatology clinic for evaluation of long-standing mild atopic dermatitis (AD) that had become severe over the last year after omalizumab was initiated for severe asthma. The patient had a history of multiple hospitalizations for severe asthma. Despite excellent control of asthma with omalizumab given every 2 weeks, he developed widespread eczematous plaques on the neck, trunk, and extremities over the course of a year. The AD often was complicated by superimposed folliculitis due to scratching from severe pruritus. Treatment with topical corticosteroids including triamcinolone ointment 0.1% to AD on the body, plus clobetasol ointment 0.05% for prurigolike lesions on the legs resulted in modest improvement; however, the AD consistently recurred within a few days after the biweekly omalizumab injection (Figure 1). When the omalizumab injections were delayed, the flares temporarily improved, and when injections were decreased to once monthly, the exacerbations subsided partially but not fully.

Because omalizumab resulted in dramatic improvement in the patient’s asthma, there was hesitation to discontinue it initially; however, the patient and his parents in conjunction with the dermatology and pulmonary teams decided to transition to dupilumab. The patient reported vast improvement of AD 1 month after initiation of dupilumab (Figure 2), which remained well controlled more than 1 year later. Mid-potency topical corticosteroids for the treatment of occasional mild eczematous flares on the extremities were used. The patient’s asthma has remained well controlled on dupilumab without any exacerbations.

Omalizumab is a recombinant DNA-derived humanized monoclonal antibody that binds both circulating and membrane-bound IgE. It has been proposed as a possible treatment for severe and/or recalcitrant AD, with mixed treatment results.¹ A case series and review of 174 patients demonstrated a moderate to complete AD response to treatment with omalizumab in 74.1% of patients.² The Atopic Dermatitis Anti-IgE Pediatric Trial (ADAPT) showed a statistically significant reduction in the Scoring Atopic Dermatitis (SCORAD) index (P=.01), along with improved quality of life in children treated with omalizumab vs those treated with placebo.³ However, a prior randomized, placebo-controlled, double-blind study did not show a significant difference in clinical disease parameters in patients treated with omalizumab.⁴

The humanized monoclonal antibody dupilumab, an anti–IL-4/IL-13 agent, has demonstrated more consistent efficacy for the treatment of AD in children and adults.¹ Dupilumab is effective for both intrinsic and extrinsic AD¹ because its clinical efficacy is unrelated to circulating levels of IgE in the bloodstream. Although IgE may have a role in childhood AD, our case demonstrated a different pathophysiologic mechanism independent of IgE. Our patient’s AD flares occurred within a few days of omalizumab injection, which may have resulted in a paradoxical increase in basophil sensitivity to other cytokines such as IL-33⁵ and led to an increase in IL-4/IL-13 production within the skin. In our patient, this increase was successfully blocked by dupilumab. Furthermore, omalizumab has been shown to modulate helper T cell (T_H2) cytokine response such as thymic stromal lymphopoietin.⁶ A cytokine imbalance could have exacerbated AD in our case.

Although additional work to clarify the pathogenesis of AD is needed, it is important to recognize the potential for the occurrence of paradoxical AD flares in patients treated with omalizumab, which is analogous to the well-documented entity of tumor necrosis factor α inhibitor–induced psoriasis. It is equally important to recognize the potential benefit for patients treated with dupilumab.

To the Editor:

A 16-year-old adolescent boy presented to our pediatric dermatology clinic for evaluation of long-standing mild atopic dermatitis (AD) that had become severe over the last year after omalizumab was initiated for severe asthma. The patient had a history of multiple hospitalizations for severe asthma. Despite excellent control of asthma with omalizumab given every 2 weeks, he developed widespread eczematous plaques on the neck, trunk, and extremities over the course of a year. The AD often was complicated by superimposed folliculitis due to scratching from severe pruritus. Treatment with topical corticosteroids including triamcinolone ointment 0.1% to AD on the body, plus clobetasol ointment 0.05% for prurigolike lesions on the legs resulted in modest improvement; however, the AD consistently recurred within a few days after the biweekly omalizumab injection (Figure 1). When the omalizumab injections were delayed, the flares temporarily improved, and when injections were decreased to once monthly, the exacerbations subsided partially but not fully.

Because omalizumab resulted in dramatic improvement in the patient’s asthma, there was hesitation to discontinue it initially; however, the patient and his parents in conjunction with the dermatology and pulmonary teams decided to transition to dupilumab. The patient reported vast improvement of AD 1 month after initiation of dupilumab (Figure 2), which remained well controlled more than 1 year later. Mid-potency topical corticosteroids for the treatment of occasional mild eczematous flares on the extremities were used. The patient’s asthma has remained well controlled on dupilumab without any exacerbations.

Omalizumab is a recombinant DNA-derived humanized monoclonal antibody that binds both circulating and membrane-bound IgE. It has been proposed as a possible treatment for severe and/or recalcitrant AD, with mixed treatment results.¹ A case series and review of 174 patients demonstrated a moderate to complete AD response to treatment with omalizumab in 74.1% of patients.² The Atopic Dermatitis Anti-IgE Pediatric Trial (ADAPT) showed a statistically significant reduction in the Scoring Atopic Dermatitis (SCORAD) index (P=.01), along with improved quality of life in children treated with omalizumab vs those treated with placebo.³ However, a prior randomized, placebo-controlled, double-blind study did not show a significant difference in clinical disease parameters in patients treated with omalizumab.⁴

The humanized monoclonal antibody dupilumab, an anti–IL-4/IL-13 agent, has demonstrated more consistent efficacy for the treatment of AD in children and adults.¹ Dupilumab is effective for both intrinsic and extrinsic AD¹ because its clinical efficacy is unrelated to circulating levels of IgE in the bloodstream. Although IgE may have a role in childhood AD, our case demonstrated a different pathophysiologic mechanism independent of IgE. Our patient’s AD flares occurred within a few days of omalizumab injection, which may have resulted in a paradoxical increase in basophil sensitivity to other cytokines such as IL-33⁵ and led to an increase in IL-4/IL-13 production within the skin. In our patient, this increase was successfully blocked by dupilumab. Furthermore, omalizumab has been shown to modulate helper T cell (T_H2) cytokine response such as thymic stromal lymphopoietin.⁶ A cytokine imbalance could have exacerbated AD in our case.

Although additional work to clarify the pathogenesis of AD is needed, it is important to recognize the potential for the occurrence of paradoxical AD flares in patients treated with omalizumab, which is analogous to the well-documented entity of tumor necrosis factor α inhibitor–induced psoriasis. It is equally important to recognize the potential benefit for patients treated with dupilumab.

To the Editor:

A 16-year-old adolescent boy presented to our pediatric dermatology clinic for evaluation of long-standing mild atopic dermatitis (AD) that had become severe over the last year after omalizumab was initiated for severe asthma. The patient had a history of multiple hospitalizations for severe asthma. Despite excellent control of asthma with omalizumab given every 2 weeks, he developed widespread eczematous plaques on the neck, trunk, and extremities over the course of a year. The AD often was complicated by superimposed folliculitis due to scratching from severe pruritus. Treatment with topical corticosteroids including triamcinolone ointment 0.1% to AD on the body, plus clobetasol ointment 0.05% for prurigolike lesions on the legs resulted in modest improvement; however, the AD consistently recurred within a few days after the biweekly omalizumab injection (Figure 1). When the omalizumab injections were delayed, the flares temporarily improved, and when injections were decreased to once monthly, the exacerbations subsided partially but not fully.

Because omalizumab resulted in dramatic improvement in the patient’s asthma, there was hesitation to discontinue it initially; however, the patient and his parents in conjunction with the dermatology and pulmonary teams decided to transition to dupilumab. The patient reported vast improvement of AD 1 month after initiation of dupilumab (Figure 2), which remained well controlled more than 1 year later. Mid-potency topical corticosteroids for the treatment of occasional mild eczematous flares on the extremities were used. The patient’s asthma has remained well controlled on dupilumab without any exacerbations.

Omalizumab is a recombinant DNA-derived humanized monoclonal antibody that binds both circulating and membrane-bound IgE. It has been proposed as a possible treatment for severe and/or recalcitrant AD, with mixed treatment results.¹ A case series and review of 174 patients demonstrated a moderate to complete AD response to treatment with omalizumab in 74.1% of patients.² The Atopic Dermatitis Anti-IgE Pediatric Trial (ADAPT) showed a statistically significant reduction in the Scoring Atopic Dermatitis (SCORAD) index (P=.01), along with improved quality of life in children treated with omalizumab vs those treated with placebo.³ However, a prior randomized, placebo-controlled, double-blind study did not show a significant difference in clinical disease parameters in patients treated with omalizumab.⁴

The humanized monoclonal antibody dupilumab, an anti–IL-4/IL-13 agent, has demonstrated more consistent efficacy for the treatment of AD in children and adults.¹ Dupilumab is effective for both intrinsic and extrinsic AD¹ because its clinical efficacy is unrelated to circulating levels of IgE in the bloodstream. Although IgE may have a role in childhood AD, our case demonstrated a different pathophysiologic mechanism independent of IgE. Our patient’s AD flares occurred within a few days of omalizumab injection, which may have resulted in a paradoxical increase in basophil sensitivity to other cytokines such as IL-33⁵ and led to an increase in IL-4/IL-13 production within the skin. In our patient, this increase was successfully blocked by dupilumab. Furthermore, omalizumab has been shown to modulate helper T cell (T_H2) cytokine response such as thymic stromal lymphopoietin.⁶ A cytokine imbalance could have exacerbated AD in our case.

Although additional work to clarify the pathogenesis of AD is needed, it is important to recognize the potential for the occurrence of paradoxical AD flares in patients treated with omalizumab, which is analogous to the well-documented entity of tumor necrosis factor α inhibitor–induced psoriasis. It is equally important to recognize the potential benefit for patients treated with dupilumab.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

To the Editor:

A woman in her 40s presented with acute onset of rapidly spreading lesions on the face, trunk, and extremities. She reported high fever and endorsed malaise. She had a history of end-stage renal disease and was on renal dialysis. She recently underwent revision of an arteriovenous fistula.

Physical examination revealed diffuse, erythematous, firm papules and plaques with central hemorrhage and umbilication on the dorsal aspect of the nose, forehead, temples, and cheeks. There also were purpuric papules and plaques with a peripheral rim of vesiculation (Figure 1) on the medial and posterior thighs and buttocks. Histopathology of a biopsy specimen revealed an interstitial neutrophilic infiltrate in the superficial dermis and mid dermis with scattered, haloed, acellular structures simulating cryptococcal organisms (Figure 2). Periodic acid–Schiff (PAS), Grocott methenamine-silver, and mucicarmine staining was negative. Repeat biopsy showed similar findings. A (1-3)-β-d glucan assay for invasive fungal infection and tests for serum cryptococcal antigen, serum Coccidioides antibody, serum Blastomyces antigen, and urine and serum Histoplasma antigen were negative. A fungal complement fixation battery was negative. Blood and tissue cultures for bacteria, anaerobes, fungi, and acid-fast bacilli remained sterile. Swabs were negative for varicella-zoster virus and herpes simplex virus. Urine and blood iodine levels were 344,998 μg/L (reference range, 34–523 μg/L) and 47,459 μg/L (reference range, 52–109 μg/L), respectively. The elevated iodine levels were presumed to be secondary to iodinated contrast media that the patient received for revision of the arteriovenous fistula.

The findings compatible with a diagnosis of iododerma included umbilicated hemorrhagic papules and plaques, cryptococcal-like structures with negative staining on histopathology, and elevated iodine levels with a negative infectious workup. The patient was treated with topical corticosteroids. At 1-month follow-up, the lesions had resolved.

Iododerma is a halogenoderma, a skin eruption that occurs after ingestion of or exposure to a halogen-containing substance (eg, iodine, bromine, fluorine) or medication (eg, lithium).¹ Common sources of iodine include iodinated contrast media, potassium iodide ingestion, topical application of povidone–iodine, radioactive iodine administration, and the antiarrhythmic amiodarone. Excess exposure to iodine-containing compounds typically occurs in the setting of kidney disease or failure as well as due to reduced iodine clearance.¹ Although the pathogenesis of iododerma is unknown, the most common hypothesis is that lesions are delayed hypersensitivity reactions secondary to formation of a protein-halogen complex.²

The presentation of iododerma is polymorphous and includes acneform, vegetative, or pustular eruptions; umbilicated papules and plaques can be present.^2,3 Lesions can be either asymptomatic or painful and pruritic. Timing between iodine exposure and onset of lesions varies from hours to days to years.^2,4

Systemic symptoms of iododerma can occur, including salivary gland swelling, hypotension and bradycardia, kidney injury, or thyroid and liver abnormalities. Histopathologic analysis demonstrates a dense neutrophilic dermatitis with negative staining for infectious causes.^4,5 Cryptococcal-like structures have been described in iododerma³; neutrophilic dermatoses of various causes that mimic cryptococcal infection have been reported.⁶ Ultimately, iododerma remains a diagnosis of exclusion.

Withdrawal of an offending compound is remedial. Dialysis is beneficial in end-stage renal disease. Topical, intralesional, and systemic corticosteroids, as well as antibiotics, provide variable benefit.^4,7 Lesions can take 4 to 6 weeks to clear after withdrawal of the offending agent. It is unclear whether recurrences happen; iodine-containing compounds need to be avoided after a patient has been affected.

Iododerma has a broad differential diagnosis due to the polymorphous presentation of the disorder, including acute febrile neutrophilic dermatosis (also known as Sweet syndrome), cutaneous cryptococcosis, and cutaneous histoplasmosis. Sweet syndrome presents as abrupt onset of edematous erythematous plaques with fever and leukocytosis. It is associated with infection, inflammatory disorders, medication, and malignancy.⁸ Histopathologic analysis reveals papillary dermal edema and a neutrophilic dermatosis. Cytoplasmic vacuolization resembling C neoformans has been reported.⁹ The diagnosis is less favored in the presence of renal disease, temporal association of the eruption with iodine exposure, and elevated blood and urine iodine levels, as in our patient.

Cutaneous cryptococcosis, an infection caused by C neoformans, typically occurs secondary to dissemination from the lungs; rarely, the disease is primary. Acneform plaques, vegetative plaques, and umbilicated lesions are seen.¹⁰ Histopathologic analysis shows characteristic yeast forms of cryptococcosis surrounded by gelatinous edema, which create a haloed effect, typically throughout the dermis. Capsules are positive for PAS or mucicarmine staining. Although C neoformans can closely mimic iododerma both clinically and histopathologically, negative infectious staining, localization of haloed structures to the upper dermis, a negative test for cryptococcal antigen, and elevated blood and urine iodine levels in this case all favored iododerma.

Cutaneous histoplasmosis is an infection caused by Histoplasma capsulatum, most commonly as secondary dissemination from pulmonary infection but rarely from direct inoculation of the skin.¹¹ Presentation includes erythematous to hemorrhagic, umbilicated papules and plaques. Histopathologic findings are round to oval, narrow-based, budding yeasts that stain positive for PAS or mucicarmine. Although histoplasmosis can clinically mimic iododerma, the disease is distinguished histologically by the presence of fungal microorganisms that lack the gelatinous edema and haloed effect of iododerma.

We presented a unique case of iododerma simulating cryptococcal infection both clinically and histopathologically. Prompt recognition of histologic mimickers of true infectious microorganisms is essential to prevent unnecessary delay of withdrawal of the offending substance and to initiate appropriate therapy.

To the Editor:

A woman in her 40s presented with acute onset of rapidly spreading lesions on the face, trunk, and extremities. She reported high fever and endorsed malaise. She had a history of end-stage renal disease and was on renal dialysis. She recently underwent revision of an arteriovenous fistula.

Physical examination revealed diffuse, erythematous, firm papules and plaques with central hemorrhage and umbilication on the dorsal aspect of the nose, forehead, temples, and cheeks. There also were purpuric papules and plaques with a peripheral rim of vesiculation (Figure 1) on the medial and posterior thighs and buttocks. Histopathology of a biopsy specimen revealed an interstitial neutrophilic infiltrate in the superficial dermis and mid dermis with scattered, haloed, acellular structures simulating cryptococcal organisms (Figure 2). Periodic acid–Schiff (PAS), Grocott methenamine-silver, and mucicarmine staining was negative. Repeat biopsy showed similar findings. A (1-3)-β-d glucan assay for invasive fungal infection and tests for serum cryptococcal antigen, serum Coccidioides antibody, serum Blastomyces antigen, and urine and serum Histoplasma antigen were negative. A fungal complement fixation battery was negative. Blood and tissue cultures for bacteria, anaerobes, fungi, and acid-fast bacilli remained sterile. Swabs were negative for varicella-zoster virus and herpes simplex virus. Urine and blood iodine levels were 344,998 μg/L (reference range, 34–523 μg/L) and 47,459 μg/L (reference range, 52–109 μg/L), respectively. The elevated iodine levels were presumed to be secondary to iodinated contrast media that the patient received for revision of the arteriovenous fistula.

The findings compatible with a diagnosis of iododerma included umbilicated hemorrhagic papules and plaques, cryptococcal-like structures with negative staining on histopathology, and elevated iodine levels with a negative infectious workup. The patient was treated with topical corticosteroids. At 1-month follow-up, the lesions had resolved.

Iododerma is a halogenoderma, a skin eruption that occurs after ingestion of or exposure to a halogen-containing substance (eg, iodine, bromine, fluorine) or medication (eg, lithium).¹ Common sources of iodine include iodinated contrast media, potassium iodide ingestion, topical application of povidone–iodine, radioactive iodine administration, and the antiarrhythmic amiodarone. Excess exposure to iodine-containing compounds typically occurs in the setting of kidney disease or failure as well as due to reduced iodine clearance.¹ Although the pathogenesis of iododerma is unknown, the most common hypothesis is that lesions are delayed hypersensitivity reactions secondary to formation of a protein-halogen complex.²

The presentation of iododerma is polymorphous and includes acneform, vegetative, or pustular eruptions; umbilicated papules and plaques can be present.^2,3 Lesions can be either asymptomatic or painful and pruritic. Timing between iodine exposure and onset of lesions varies from hours to days to years.^2,4

Systemic symptoms of iododerma can occur, including salivary gland swelling, hypotension and bradycardia, kidney injury, or thyroid and liver abnormalities. Histopathologic analysis demonstrates a dense neutrophilic dermatitis with negative staining for infectious causes.^4,5 Cryptococcal-like structures have been described in iododerma³; neutrophilic dermatoses of various causes that mimic cryptococcal infection have been reported.⁶ Ultimately, iododerma remains a diagnosis of exclusion.

Withdrawal of an offending compound is remedial. Dialysis is beneficial in end-stage renal disease. Topical, intralesional, and systemic corticosteroids, as well as antibiotics, provide variable benefit.^4,7 Lesions can take 4 to 6 weeks to clear after withdrawal of the offending agent. It is unclear whether recurrences happen; iodine-containing compounds need to be avoided after a patient has been affected.

Iododerma has a broad differential diagnosis due to the polymorphous presentation of the disorder, including acute febrile neutrophilic dermatosis (also known as Sweet syndrome), cutaneous cryptococcosis, and cutaneous histoplasmosis. Sweet syndrome presents as abrupt onset of edematous erythematous plaques with fever and leukocytosis. It is associated with infection, inflammatory disorders, medication, and malignancy.⁸ Histopathologic analysis reveals papillary dermal edema and a neutrophilic dermatosis. Cytoplasmic vacuolization resembling C neoformans has been reported.⁹ The diagnosis is less favored in the presence of renal disease, temporal association of the eruption with iodine exposure, and elevated blood and urine iodine levels, as in our patient.

Cutaneous cryptococcosis, an infection caused by C neoformans, typically occurs secondary to dissemination from the lungs; rarely, the disease is primary. Acneform plaques, vegetative plaques, and umbilicated lesions are seen.¹⁰ Histopathologic analysis shows characteristic yeast forms of cryptococcosis surrounded by gelatinous edema, which create a haloed effect, typically throughout the dermis. Capsules are positive for PAS or mucicarmine staining. Although C neoformans can closely mimic iododerma both clinically and histopathologically, negative infectious staining, localization of haloed structures to the upper dermis, a negative test for cryptococcal antigen, and elevated blood and urine iodine levels in this case all favored iododerma.

Cutaneous histoplasmosis is an infection caused by Histoplasma capsulatum, most commonly as secondary dissemination from pulmonary infection but rarely from direct inoculation of the skin.¹¹ Presentation includes erythematous to hemorrhagic, umbilicated papules and plaques. Histopathologic findings are round to oval, narrow-based, budding yeasts that stain positive for PAS or mucicarmine. Although histoplasmosis can clinically mimic iododerma, the disease is distinguished histologically by the presence of fungal microorganisms that lack the gelatinous edema and haloed effect of iododerma.

We presented a unique case of iododerma simulating cryptococcal infection both clinically and histopathologically. Prompt recognition of histologic mimickers of true infectious microorganisms is essential to prevent unnecessary delay of withdrawal of the offending substance and to initiate appropriate therapy.

To the Editor:

A woman in her 40s presented with acute onset of rapidly spreading lesions on the face, trunk, and extremities. She reported high fever and endorsed malaise. She had a history of end-stage renal disease and was on renal dialysis. She recently underwent revision of an arteriovenous fistula.

Physical examination revealed diffuse, erythematous, firm papules and plaques with central hemorrhage and umbilication on the dorsal aspect of the nose, forehead, temples, and cheeks. There also were purpuric papules and plaques with a peripheral rim of vesiculation (Figure 1) on the medial and posterior thighs and buttocks. Histopathology of a biopsy specimen revealed an interstitial neutrophilic infiltrate in the superficial dermis and mid dermis with scattered, haloed, acellular structures simulating cryptococcal organisms (Figure 2). Periodic acid–Schiff (PAS), Grocott methenamine-silver, and mucicarmine staining was negative. Repeat biopsy showed similar findings. A (1-3)-β-d glucan assay for invasive fungal infection and tests for serum cryptococcal antigen, serum Coccidioides antibody, serum Blastomyces antigen, and urine and serum Histoplasma antigen were negative. A fungal complement fixation battery was negative. Blood and tissue cultures for bacteria, anaerobes, fungi, and acid-fast bacilli remained sterile. Swabs were negative for varicella-zoster virus and herpes simplex virus. Urine and blood iodine levels were 344,998 μg/L (reference range, 34–523 μg/L) and 47,459 μg/L (reference range, 52–109 μg/L), respectively. The elevated iodine levels were presumed to be secondary to iodinated contrast media that the patient received for revision of the arteriovenous fistula.

The findings compatible with a diagnosis of iododerma included umbilicated hemorrhagic papules and plaques, cryptococcal-like structures with negative staining on histopathology, and elevated iodine levels with a negative infectious workup. The patient was treated with topical corticosteroids. At 1-month follow-up, the lesions had resolved.

Iododerma is a halogenoderma, a skin eruption that occurs after ingestion of or exposure to a halogen-containing substance (eg, iodine, bromine, fluorine) or medication (eg, lithium).¹ Common sources of iodine include iodinated contrast media, potassium iodide ingestion, topical application of povidone–iodine, radioactive iodine administration, and the antiarrhythmic amiodarone. Excess exposure to iodine-containing compounds typically occurs in the setting of kidney disease or failure as well as due to reduced iodine clearance.¹ Although the pathogenesis of iododerma is unknown, the most common hypothesis is that lesions are delayed hypersensitivity reactions secondary to formation of a protein-halogen complex.²

The presentation of iododerma is polymorphous and includes acneform, vegetative, or pustular eruptions; umbilicated papules and plaques can be present.^2,3 Lesions can be either asymptomatic or painful and pruritic. Timing between iodine exposure and onset of lesions varies from hours to days to years.^2,4

Systemic symptoms of iododerma can occur, including salivary gland swelling, hypotension and bradycardia, kidney injury, or thyroid and liver abnormalities. Histopathologic analysis demonstrates a dense neutrophilic dermatitis with negative staining for infectious causes.^4,5 Cryptococcal-like structures have been described in iododerma³; neutrophilic dermatoses of various causes that mimic cryptococcal infection have been reported.⁶ Ultimately, iododerma remains a diagnosis of exclusion.

Withdrawal of an offending compound is remedial. Dialysis is beneficial in end-stage renal disease. Topical, intralesional, and systemic corticosteroids, as well as antibiotics, provide variable benefit.^4,7 Lesions can take 4 to 6 weeks to clear after withdrawal of the offending agent. It is unclear whether recurrences happen; iodine-containing compounds need to be avoided after a patient has been affected.

Iododerma has a broad differential diagnosis due to the polymorphous presentation of the disorder, including acute febrile neutrophilic dermatosis (also known as Sweet syndrome), cutaneous cryptococcosis, and cutaneous histoplasmosis. Sweet syndrome presents as abrupt onset of edematous erythematous plaques with fever and leukocytosis. It is associated with infection, inflammatory disorders, medication, and malignancy.⁸ Histopathologic analysis reveals papillary dermal edema and a neutrophilic dermatosis. Cytoplasmic vacuolization resembling C neoformans has been reported.⁹ The diagnosis is less favored in the presence of renal disease, temporal association of the eruption with iodine exposure, and elevated blood and urine iodine levels, as in our patient.

Cutaneous cryptococcosis, an infection caused by C neoformans, typically occurs secondary to dissemination from the lungs; rarely, the disease is primary. Acneform plaques, vegetative plaques, and umbilicated lesions are seen.¹⁰ Histopathologic analysis shows characteristic yeast forms of cryptococcosis surrounded by gelatinous edema, which create a haloed effect, typically throughout the dermis. Capsules are positive for PAS or mucicarmine staining. Although C neoformans can closely mimic iododerma both clinically and histopathologically, negative infectious staining, localization of haloed structures to the upper dermis, a negative test for cryptococcal antigen, and elevated blood and urine iodine levels in this case all favored iododerma.

Cutaneous histoplasmosis is an infection caused by Histoplasma capsulatum, most commonly as secondary dissemination from pulmonary infection but rarely from direct inoculation of the skin.¹¹ Presentation includes erythematous to hemorrhagic, umbilicated papules and plaques. Histopathologic findings are round to oval, narrow-based, budding yeasts that stain positive for PAS or mucicarmine. Although histoplasmosis can clinically mimic iododerma, the disease is distinguished histologically by the presence of fungal microorganisms that lack the gelatinous edema and haloed effect of iododerma.

We presented a unique case of iododerma simulating cryptococcal infection both clinically and histopathologically. Prompt recognition of histologic mimickers of true infectious microorganisms is essential to prevent unnecessary delay of withdrawal of the offending substance and to initiate appropriate therapy.