Nonmelanoma Skin Cancer

Daily application of topical fluorouracil for 4 weeks reduced the risk of developing squamous cell cancer (SCC) requiring surgery by 75% in a population of high-risk older adults.

The findings were published online Jan. 3 in JAMA Dermatology.

Although topical fluorouracil can help reduce actinic keratoses and cure some superficial basal cell and squamous cell carcinomas, it has not been studied as a strategy to prevent the development of lesions that might require surgery, wrote Martin A. Weinstock, MD, PhD, of Providence (R.I.) Veterans Affairs Medical Center, and his colleagues (JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631).

SOURCE: Weinstock, M et al. JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631.

Daily application of topical fluorouracil for 4 weeks reduced the risk of developing squamous cell cancer (SCC) requiring surgery by 75% in a population of high-risk older adults.

The findings were published online Jan. 3 in JAMA Dermatology.

Although topical fluorouracil can help reduce actinic keratoses and cure some superficial basal cell and squamous cell carcinomas, it has not been studied as a strategy to prevent the development of lesions that might require surgery, wrote Martin A. Weinstock, MD, PhD, of Providence (R.I.) Veterans Affairs Medical Center, and his colleagues (JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631).

SOURCE: Weinstock, M et al. JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631.

Daily application of topical fluorouracil for 4 weeks reduced the risk of developing squamous cell cancer (SCC) requiring surgery by 75% in a population of high-risk older adults.

The findings were published online Jan. 3 in JAMA Dermatology.

Although topical fluorouracil can help reduce actinic keratoses and cure some superficial basal cell and squamous cell carcinomas, it has not been studied as a strategy to prevent the development of lesions that might require surgery, wrote Martin A. Weinstock, MD, PhD, of Providence (R.I.) Veterans Affairs Medical Center, and his colleagues (JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631).

SOURCE: Weinstock, M et al. JAMA Dermatol. 2017 Jan 3. doi: 10.1001/jamadermatol.2017.3631.

The common diuretic hydrochlorothiazide is linked to a dose-dependent increased risk of nonmelanoma skin cancer, in particular, squamous cell carcinoma, a case-controlled registry study showed.

This nationwide, case-matched control study examined patients’ cumulative hydrochlorothiazide use between 1995 and 2012 and found a clear dose-response patterns for both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with a more than sevenfold increased risk of SCC for a cumulative use of greater than or equal to 200,000 mg of hydrochlorothiazide (HCTZ).

“Assuming causality, the present results suggest that 1 in 10 SCC cases diagnosed during the study period can be attributed to HCTZ use,” wrote the study authors, who were led by Sidsel Arnspang, MD, of the department of neurology at Odense (Denmark) University Hospital, which is affiliated with the University of Southern Denmark.

The authors noted that they previously had reported a sevenfold increased risk of lip squamous cell carcinoma with hydrochlorothiazide. Furthermore, the International Agency for Research on Cancer recently classified the diuretic and antihypertensive as “possibly carcinogenic to humans.”

“As HCTZ is among the most widely used drugs in the U.S. and Western Europe, a carcinogenic effect of HCTZ would have a considerable impact on public health,” they wrote in their paper, published in the Journal of American Academy of Dermatology.

According to the study authors, the few studies that have investigated a potential link between thiazide use and nonmelanoma skin cancer (NMSC) have reported inconsistent results.

They speculated that this could be because HCTZ often is prescribed in combination with other diuretics, and there may have been difficulties with disentangling its effect from those of the other drugs.

Using data from five nationwide data sources, the research team compared HCTZ use among people diagnosed with SCC or BCC of the skin to use among a matched control group without such cancers. People were excluded from the analysis if they had SCC of the lip because they had been evaluated in the research team’s previous study.

SOURCE: Arnspang S et al. JAAD. 2017. doi: 10.1016/j.jaad.2017.11.042.

The common diuretic hydrochlorothiazide is linked to a dose-dependent increased risk of nonmelanoma skin cancer, in particular, squamous cell carcinoma, a case-controlled registry study showed.

This nationwide, case-matched control study examined patients’ cumulative hydrochlorothiazide use between 1995 and 2012 and found a clear dose-response patterns for both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with a more than sevenfold increased risk of SCC for a cumulative use of greater than or equal to 200,000 mg of hydrochlorothiazide (HCTZ).

“Assuming causality, the present results suggest that 1 in 10 SCC cases diagnosed during the study period can be attributed to HCTZ use,” wrote the study authors, who were led by Sidsel Arnspang, MD, of the department of neurology at Odense (Denmark) University Hospital, which is affiliated with the University of Southern Denmark.

The authors noted that they previously had reported a sevenfold increased risk of lip squamous cell carcinoma with hydrochlorothiazide. Furthermore, the International Agency for Research on Cancer recently classified the diuretic and antihypertensive as “possibly carcinogenic to humans.”

“As HCTZ is among the most widely used drugs in the U.S. and Western Europe, a carcinogenic effect of HCTZ would have a considerable impact on public health,” they wrote in their paper, published in the Journal of American Academy of Dermatology.

According to the study authors, the few studies that have investigated a potential link between thiazide use and nonmelanoma skin cancer (NMSC) have reported inconsistent results.

They speculated that this could be because HCTZ often is prescribed in combination with other diuretics, and there may have been difficulties with disentangling its effect from those of the other drugs.

Using data from five nationwide data sources, the research team compared HCTZ use among people diagnosed with SCC or BCC of the skin to use among a matched control group without such cancers. People were excluded from the analysis if they had SCC of the lip because they had been evaluated in the research team’s previous study.

SOURCE: Arnspang S et al. JAAD. 2017. doi: 10.1016/j.jaad.2017.11.042.

The common diuretic hydrochlorothiazide is linked to a dose-dependent increased risk of nonmelanoma skin cancer, in particular, squamous cell carcinoma, a case-controlled registry study showed.

This nationwide, case-matched control study examined patients’ cumulative hydrochlorothiazide use between 1995 and 2012 and found a clear dose-response patterns for both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with a more than sevenfold increased risk of SCC for a cumulative use of greater than or equal to 200,000 mg of hydrochlorothiazide (HCTZ).

“Assuming causality, the present results suggest that 1 in 10 SCC cases diagnosed during the study period can be attributed to HCTZ use,” wrote the study authors, who were led by Sidsel Arnspang, MD, of the department of neurology at Odense (Denmark) University Hospital, which is affiliated with the University of Southern Denmark.

The authors noted that they previously had reported a sevenfold increased risk of lip squamous cell carcinoma with hydrochlorothiazide. Furthermore, the International Agency for Research on Cancer recently classified the diuretic and antihypertensive as “possibly carcinogenic to humans.”

“As HCTZ is among the most widely used drugs in the U.S. and Western Europe, a carcinogenic effect of HCTZ would have a considerable impact on public health,” they wrote in their paper, published in the Journal of American Academy of Dermatology.

According to the study authors, the few studies that have investigated a potential link between thiazide use and nonmelanoma skin cancer (NMSC) have reported inconsistent results.

They speculated that this could be because HCTZ often is prescribed in combination with other diuretics, and there may have been difficulties with disentangling its effect from those of the other drugs.

Using data from five nationwide data sources, the research team compared HCTZ use among people diagnosed with SCC or BCC of the skin to use among a matched control group without such cancers. People were excluded from the analysis if they had SCC of the lip because they had been evaluated in the research team’s previous study.

SOURCE: Arnspang S et al. JAAD. 2017. doi: 10.1016/j.jaad.2017.11.042.

Pseudomyogenic hemangioendothelioma (PMHE), also referred to as epithelioid sarcoma–like hemangioendothelioma,¹ is a rare soft tissue tumor that was described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. It predominantly affects males between the second and fifth decades of life and most commonly presents as multiple nodules that may involve either the superficial or deep soft tissues of the legs and less often the arms. It also can arise on the trunk. We present a case of PMHE occurring in a young man and briefly review the literature on clinical presentation and histologic differentiation of this unique tumor, comparing these findings to its mimickers.

Case Report

A 20-year-old man presented with skin lesions on the left leg that had been present for 1 year. The patient described the lesions as tender pimples that would drain yellow discharge on occasion but had now transformed into large brown plaques. Physical examination showed 4 verrucous plaques ranging in size from 1 to 3 cm with hyperpigmentation and a central crust (Figure 1). Initially, the patient thought the lesions appeared due to shaving his legs for sports. He presented to the emergency department multiple times over the past year; pain control was provided and local skin care was recommended. Culture of the discharge had been performed 6 months prior to biopsy with negative results. No biopsy was performed on initial presentation and the lesions were diagnosed in the emergency department clinically as boils.

After failing to improve, the patient was seen by an outside dermatologist and the clinical differential diagnosis included deep fungal infection, atypical mycobacterial infection, and keloids. A 4-mm punch biopsy was taken from the periphery of one of the lesions and demonstrated hyperkeratosis, papillomatosis, and acanthosis (Figure 2). Within the superficial and deep dermis and focally extending into the subcutaneous tissue, there were sheets of spindled to epithelioid-appearing cells with moderate cytologic atypia (Figure 3). The tumor showed infiltrative margins. There was moderate cellularity. The individual cells had a rhabdoid appearance with large eccentric vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm (Figure 4). No definitive evidence of glandular, squamous, or vascular differentiation was present. There was an associated moderate inflammatory host response composed of neutrophils and lymphocytes. Occasional extravasated red blood cells were present. Immunohistochemistry staining was performed and the atypical cells demonstrated diffuse positive staining for friend leukemia integration 1 transcription factor (FLI-1), erythroblastosis virus E26 transforming sequence-related gene (ERG)(Figure 5), CD31, and CD68. There was patchy positive staining for cytokeratin AE1/AE3, CD10, and factor VIII. There was no remarkable staining for human herpesvirus 8, epithelial membrane antigen, S-100, CD34, cytokeratin 903, and desmin. Overall, the histologic features in conjunction with the immunohistochemistry staining were consistent with a diagnosis of PMHE.

Magnetic resonance imaging was then performed to evaluate the depth and extent of the lesions for surgical excision planning (Figure 6), which showed 5 nodular lesions within the dermis and subcutis adjacent to the proximal aspect of the left tibia and medial aspect of the left knee. An additional lesion was noted between the sartorius and semimembranosus muscles, which was thought to represent either a lymph node or an additional neoplastic lesion. Chest computed tomography also displayed indeterminate lesions in the lungs.

Excision of the superficial lesions was performed. All of the lesions demonstrated similar histologic changes to the previously described biopsy specimen. The tumor was limited to the dermis and subcutaneous tissue. The patient was lost to follow-up and the etiology of the lung lesions was unknown.

Comment

Nomenclature
Pseudomyogenic hemangioendothelioma is a relatively new type of vascular tumor that has been included in the updated 2013 edition of the World Health Organization classification as an intermediate malignant tumor that rarely metastasizes.³ It typically involves multiple tissue planes, most notably the dermis and subcutaneous layers but also muscle and bone.⁴ The term pseudomyogenic refers to the histologic resemblance of some of the cells to rhabdomyoblasts; however, these tumors are negative for all immunohistochemical muscle markers, most notably myogenin, desmin, and α-smooth muscle actin.⁵

Clinical Presentation
Gross features of PMHE typically include multiple firm nodules with ill-defined margins. The tumor was initially described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. In 2003, a series of 7 cases of PMHE was reported by Billings et al⁶ under the term epithelioid sarcomalike hemangioendothelioma. Other than the predominance of an epithelioid morphology, the cases reported as epithelioid sarcomalike hemangioendothelioma had similar clinical features and immunophenotype to what has been reported as PMHE.

Based on a PubMed search of articles indexed for MEDLINE using the term pseudomyogenic hemangioendothelioma, the 2 largest case series were reported by Pradhan et al⁷ (N=8) in 2017 and Hornick and Fletcher⁴ (N=50) in 2011. Hornick and Fletcher⁴ reported a male (41/50 [82.0%]) to female (9/50 [18.0%]) ratio of 4.6 to 1, and an average age at presentation of 31 years with 82% (41/50) of patients 40 years or younger. Pradhan et al⁷ also reported a male predominance (7/8 [87.5%]) with a similar average age at presentation of 29 years (age range, 9–62 years). The size of individual tumors ranged from 0.3 to 5.5 cm (mean size, 1.9 cm) in the series by Hornick and Fletcher⁴ and 0.3 to 6.0 com in the series by Pradhan et al.⁷ Hornick and Fletcher⁴ reported the most common site of involvement was the leg (27/50 [54.0%]), followed by the arm (12/50 [24.0%]), trunk (9/50 [18.0%]), and head and neck (2/50 [4.0%]). The leg (6/8 [75.0%]) also was the most common site of involvement in the series by Pradhan et al,⁷ with 2 cases occurring on the arm. In the series by Hornick and Fletcher,⁴ the tumors typically involved the dermis and subcutaneous tissue (26/50 [52%]) with a smaller number involving skeletal muscle (17/50 [34%]) and bone (7/50 [14%]). They reported 66% of their patients (33/50) had multifocal disease at presentation.⁴ Pradhan et al⁷ also reported 2 (25.0%) cases being limited to the superficial soft tissue, 2 (25.0%) being limited to the deep soft tissue, and 4 (50.0%) involving the bone; 5 (62.5%) patients had multifocal disease at presentation. The presentation of our patient in regards to gender, age, and tumor characteristics is consistent with other published cases.^5-10

Histopathology
Microscopic features of PMHE include sheets of spindled to epithelioid-appearing cells with mild to moderate nuclear atypia and eosinophilic cytoplasm. The tumor has an infiltrative growth pattern. Some of the cells may resemble rhabdomyoblastlike cells, hence the moniker pseudomyogenic. There is no recapitulation of vascular structures or remarkable cytoplasmic vacuolization. Mitotic rate is low and there is no tumor necrosis.⁴ The tumor cells do not appear to arise from a vessel or display an angiocentric growth pattern. Many cases report the presence of an inflammatory infiltrate containing neutrophils interspersed within the tumor.^4,5,7 The overlying epidermis will commonly show hyperkeratosis, epidermal hyperplasia, and acanthosis.^4,11

Differential Diagnosis
The histopathologic differential diagnosis would include epithelioid sarcoma, epithelioid hemangioendothelioma, and to a lesser extent dermatofibrosarcoma protuberans (DFSP) and rhabdomyosarcoma. Dermatofibrosarcoma protuberans is the most commonly encountered of these tumors. Histologically, DFSP is characterized by a cellular proliferation of small spindle cells with plump nuclei arranged in a storiform or cartwheel pattern. Dermatofibrosarcoma protuberans tends to be limited to the dermis and subcutaneous tissue and only rarely involves underlying skeletal muscle. The presence of the storiform growth pattern in conjunction with the lack of rhabdoid changes would favor a diagnosis of DFSP. Another characteristic histologic finding typically only associated with DFSP is the interdigitating growth pattern of the spindle cells within the lobules of the subcutaneous tissue, creating a lacelike or honeycomb appearance.

Immunohistochemistry staining is necessary to help differentiate PMHE from other tumors in the differential diagnosis. Pseudomyogenic hemangioendothelioma stains positive for cytokeratin AE1/AE3; integrase interactor 1; and vascular markers FLI-1, CD31, and ERG, and negative for CD34.^4,6,12-15 In contrast to epithelioid hemangioendothelioma, DFSP, and to a lesser extent epithelioid sarcoma, all of which are positive for CD34, epithelioid sarcoma is negative for both CD31 and integrase interactor 1. Dermatofibrosarcoma protuberans is negative for cytokeratin AE1/AE3. Rhabdomyosarcomas are positive for myogenic markers such as MyoD1 and myogenin, unlike any of the other tumors mentioned. Histologically, epithelioid sarcomas will tend to have a granulomalike growth pattern with central necrosis, unlike PMHE.¹² Epithelioid hemangioendothelioma often will have a cordlike growth pattern in a myxochondroid background. Unlike PMHE, these tumors often will appear to be arising from vessels, and intracytoplasmic vacuoles are common. Three cases of PMHE have been reported to have a t(7;19)(q22;q13) chromosomal anomaly, which is not consistent with every case.¹⁶

Treatment Options
Standard treatment typically includes wide excision of the lesions, as was done in our case. Because of the substantial risk of local recurrence, which was up to 58% in the series by Hornick and Fletcher,⁴ adjuvant therapy may be considered if positive margins are found on excision. Metastasis to lymph nodes and the lungs has been reported but is rare.^2,4 Most cases have been shown to have a favorable prognosis; however, local recurrence seems to be common. Rarely, amputation of the limb may be required.⁵ In contrast, epithelioid sarcomas have been found to spread to lymph nodes and the lungs in up to 50% of cases with a 5-year survival rate of 10% to 30%.¹³

Conclusion

In summary, we describe a case of PMHE involving the lower leg in a 20-year-old man. These tumors often are multinodular and multiplanar, with the dermis and subcutaneous tissues being the most common areas affected. It has a high rate of local recurrence but rarely has distant metastasis. Pseudomyogenic hemangioendothelioma, similar to other soft tissue tumors, can be difficult to diagnose on shave biopsy or superficial punch biopsy not extending into subcutaneous tissue. Deep incisional or punch biopsies are required to more definitively diagnose these types of tumors. The diagnosis of PMHE versus other soft tissue tumors requires correlation of histology and immunohistochemistry staining with clinical information and radiographic findings.

Pseudomyogenic hemangioendothelioma (PMHE), also referred to as epithelioid sarcoma–like hemangioendothelioma,¹ is a rare soft tissue tumor that was described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. It predominantly affects males between the second and fifth decades of life and most commonly presents as multiple nodules that may involve either the superficial or deep soft tissues of the legs and less often the arms. It also can arise on the trunk. We present a case of PMHE occurring in a young man and briefly review the literature on clinical presentation and histologic differentiation of this unique tumor, comparing these findings to its mimickers.

Case Report

A 20-year-old man presented with skin lesions on the left leg that had been present for 1 year. The patient described the lesions as tender pimples that would drain yellow discharge on occasion but had now transformed into large brown plaques. Physical examination showed 4 verrucous plaques ranging in size from 1 to 3 cm with hyperpigmentation and a central crust (Figure 1). Initially, the patient thought the lesions appeared due to shaving his legs for sports. He presented to the emergency department multiple times over the past year; pain control was provided and local skin care was recommended. Culture of the discharge had been performed 6 months prior to biopsy with negative results. No biopsy was performed on initial presentation and the lesions were diagnosed in the emergency department clinically as boils.

After failing to improve, the patient was seen by an outside dermatologist and the clinical differential diagnosis included deep fungal infection, atypical mycobacterial infection, and keloids. A 4-mm punch biopsy was taken from the periphery of one of the lesions and demonstrated hyperkeratosis, papillomatosis, and acanthosis (Figure 2). Within the superficial and deep dermis and focally extending into the subcutaneous tissue, there were sheets of spindled to epithelioid-appearing cells with moderate cytologic atypia (Figure 3). The tumor showed infiltrative margins. There was moderate cellularity. The individual cells had a rhabdoid appearance with large eccentric vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm (Figure 4). No definitive evidence of glandular, squamous, or vascular differentiation was present. There was an associated moderate inflammatory host response composed of neutrophils and lymphocytes. Occasional extravasated red blood cells were present. Immunohistochemistry staining was performed and the atypical cells demonstrated diffuse positive staining for friend leukemia integration 1 transcription factor (FLI-1), erythroblastosis virus E26 transforming sequence-related gene (ERG)(Figure 5), CD31, and CD68. There was patchy positive staining for cytokeratin AE1/AE3, CD10, and factor VIII. There was no remarkable staining for human herpesvirus 8, epithelial membrane antigen, S-100, CD34, cytokeratin 903, and desmin. Overall, the histologic features in conjunction with the immunohistochemistry staining were consistent with a diagnosis of PMHE.

Magnetic resonance imaging was then performed to evaluate the depth and extent of the lesions for surgical excision planning (Figure 6), which showed 5 nodular lesions within the dermis and subcutis adjacent to the proximal aspect of the left tibia and medial aspect of the left knee. An additional lesion was noted between the sartorius and semimembranosus muscles, which was thought to represent either a lymph node or an additional neoplastic lesion. Chest computed tomography also displayed indeterminate lesions in the lungs.

Excision of the superficial lesions was performed. All of the lesions demonstrated similar histologic changes to the previously described biopsy specimen. The tumor was limited to the dermis and subcutaneous tissue. The patient was lost to follow-up and the etiology of the lung lesions was unknown.

Comment

Nomenclature
Pseudomyogenic hemangioendothelioma is a relatively new type of vascular tumor that has been included in the updated 2013 edition of the World Health Organization classification as an intermediate malignant tumor that rarely metastasizes.³ It typically involves multiple tissue planes, most notably the dermis and subcutaneous layers but also muscle and bone.⁴ The term pseudomyogenic refers to the histologic resemblance of some of the cells to rhabdomyoblasts; however, these tumors are negative for all immunohistochemical muscle markers, most notably myogenin, desmin, and α-smooth muscle actin.⁵

Clinical Presentation
Gross features of PMHE typically include multiple firm nodules with ill-defined margins. The tumor was initially described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. In 2003, a series of 7 cases of PMHE was reported by Billings et al⁶ under the term epithelioid sarcomalike hemangioendothelioma. Other than the predominance of an epithelioid morphology, the cases reported as epithelioid sarcomalike hemangioendothelioma had similar clinical features and immunophenotype to what has been reported as PMHE.

Based on a PubMed search of articles indexed for MEDLINE using the term pseudomyogenic hemangioendothelioma, the 2 largest case series were reported by Pradhan et al⁷ (N=8) in 2017 and Hornick and Fletcher⁴ (N=50) in 2011. Hornick and Fletcher⁴ reported a male (41/50 [82.0%]) to female (9/50 [18.0%]) ratio of 4.6 to 1, and an average age at presentation of 31 years with 82% (41/50) of patients 40 years or younger. Pradhan et al⁷ also reported a male predominance (7/8 [87.5%]) with a similar average age at presentation of 29 years (age range, 9–62 years). The size of individual tumors ranged from 0.3 to 5.5 cm (mean size, 1.9 cm) in the series by Hornick and Fletcher⁴ and 0.3 to 6.0 com in the series by Pradhan et al.⁷ Hornick and Fletcher⁴ reported the most common site of involvement was the leg (27/50 [54.0%]), followed by the arm (12/50 [24.0%]), trunk (9/50 [18.0%]), and head and neck (2/50 [4.0%]). The leg (6/8 [75.0%]) also was the most common site of involvement in the series by Pradhan et al,⁷ with 2 cases occurring on the arm. In the series by Hornick and Fletcher,⁴ the tumors typically involved the dermis and subcutaneous tissue (26/50 [52%]) with a smaller number involving skeletal muscle (17/50 [34%]) and bone (7/50 [14%]). They reported 66% of their patients (33/50) had multifocal disease at presentation.⁴ Pradhan et al⁷ also reported 2 (25.0%) cases being limited to the superficial soft tissue, 2 (25.0%) being limited to the deep soft tissue, and 4 (50.0%) involving the bone; 5 (62.5%) patients had multifocal disease at presentation. The presentation of our patient in regards to gender, age, and tumor characteristics is consistent with other published cases.^5-10

Histopathology
Microscopic features of PMHE include sheets of spindled to epithelioid-appearing cells with mild to moderate nuclear atypia and eosinophilic cytoplasm. The tumor has an infiltrative growth pattern. Some of the cells may resemble rhabdomyoblastlike cells, hence the moniker pseudomyogenic. There is no recapitulation of vascular structures or remarkable cytoplasmic vacuolization. Mitotic rate is low and there is no tumor necrosis.⁴ The tumor cells do not appear to arise from a vessel or display an angiocentric growth pattern. Many cases report the presence of an inflammatory infiltrate containing neutrophils interspersed within the tumor.^4,5,7 The overlying epidermis will commonly show hyperkeratosis, epidermal hyperplasia, and acanthosis.^4,11

Differential Diagnosis
The histopathologic differential diagnosis would include epithelioid sarcoma, epithelioid hemangioendothelioma, and to a lesser extent dermatofibrosarcoma protuberans (DFSP) and rhabdomyosarcoma. Dermatofibrosarcoma protuberans is the most commonly encountered of these tumors. Histologically, DFSP is characterized by a cellular proliferation of small spindle cells with plump nuclei arranged in a storiform or cartwheel pattern. Dermatofibrosarcoma protuberans tends to be limited to the dermis and subcutaneous tissue and only rarely involves underlying skeletal muscle. The presence of the storiform growth pattern in conjunction with the lack of rhabdoid changes would favor a diagnosis of DFSP. Another characteristic histologic finding typically only associated with DFSP is the interdigitating growth pattern of the spindle cells within the lobules of the subcutaneous tissue, creating a lacelike or honeycomb appearance.

Immunohistochemistry staining is necessary to help differentiate PMHE from other tumors in the differential diagnosis. Pseudomyogenic hemangioendothelioma stains positive for cytokeratin AE1/AE3; integrase interactor 1; and vascular markers FLI-1, CD31, and ERG, and negative for CD34.^4,6,12-15 In contrast to epithelioid hemangioendothelioma, DFSP, and to a lesser extent epithelioid sarcoma, all of which are positive for CD34, epithelioid sarcoma is negative for both CD31 and integrase interactor 1. Dermatofibrosarcoma protuberans is negative for cytokeratin AE1/AE3. Rhabdomyosarcomas are positive for myogenic markers such as MyoD1 and myogenin, unlike any of the other tumors mentioned. Histologically, epithelioid sarcomas will tend to have a granulomalike growth pattern with central necrosis, unlike PMHE.¹² Epithelioid hemangioendothelioma often will have a cordlike growth pattern in a myxochondroid background. Unlike PMHE, these tumors often will appear to be arising from vessels, and intracytoplasmic vacuoles are common. Three cases of PMHE have been reported to have a t(7;19)(q22;q13) chromosomal anomaly, which is not consistent with every case.¹⁶

Treatment Options
Standard treatment typically includes wide excision of the lesions, as was done in our case. Because of the substantial risk of local recurrence, which was up to 58% in the series by Hornick and Fletcher,⁴ adjuvant therapy may be considered if positive margins are found on excision. Metastasis to lymph nodes and the lungs has been reported but is rare.^2,4 Most cases have been shown to have a favorable prognosis; however, local recurrence seems to be common. Rarely, amputation of the limb may be required.⁵ In contrast, epithelioid sarcomas have been found to spread to lymph nodes and the lungs in up to 50% of cases with a 5-year survival rate of 10% to 30%.¹³

Conclusion

In summary, we describe a case of PMHE involving the lower leg in a 20-year-old man. These tumors often are multinodular and multiplanar, with the dermis and subcutaneous tissues being the most common areas affected. It has a high rate of local recurrence but rarely has distant metastasis. Pseudomyogenic hemangioendothelioma, similar to other soft tissue tumors, can be difficult to diagnose on shave biopsy or superficial punch biopsy not extending into subcutaneous tissue. Deep incisional or punch biopsies are required to more definitively diagnose these types of tumors. The diagnosis of PMHE versus other soft tissue tumors requires correlation of histology and immunohistochemistry staining with clinical information and radiographic findings.

Pseudomyogenic hemangioendothelioma (PMHE), also referred to as epithelioid sarcoma–like hemangioendothelioma,¹ is a rare soft tissue tumor that was described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. It predominantly affects males between the second and fifth decades of life and most commonly presents as multiple nodules that may involve either the superficial or deep soft tissues of the legs and less often the arms. It also can arise on the trunk. We present a case of PMHE occurring in a young man and briefly review the literature on clinical presentation and histologic differentiation of this unique tumor, comparing these findings to its mimickers.

Case Report

A 20-year-old man presented with skin lesions on the left leg that had been present for 1 year. The patient described the lesions as tender pimples that would drain yellow discharge on occasion but had now transformed into large brown plaques. Physical examination showed 4 verrucous plaques ranging in size from 1 to 3 cm with hyperpigmentation and a central crust (Figure 1). Initially, the patient thought the lesions appeared due to shaving his legs for sports. He presented to the emergency department multiple times over the past year; pain control was provided and local skin care was recommended. Culture of the discharge had been performed 6 months prior to biopsy with negative results. No biopsy was performed on initial presentation and the lesions were diagnosed in the emergency department clinically as boils.

After failing to improve, the patient was seen by an outside dermatologist and the clinical differential diagnosis included deep fungal infection, atypical mycobacterial infection, and keloids. A 4-mm punch biopsy was taken from the periphery of one of the lesions and demonstrated hyperkeratosis, papillomatosis, and acanthosis (Figure 2). Within the superficial and deep dermis and focally extending into the subcutaneous tissue, there were sheets of spindled to epithelioid-appearing cells with moderate cytologic atypia (Figure 3). The tumor showed infiltrative margins. There was moderate cellularity. The individual cells had a rhabdoid appearance with large eccentric vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm (Figure 4). No definitive evidence of glandular, squamous, or vascular differentiation was present. There was an associated moderate inflammatory host response composed of neutrophils and lymphocytes. Occasional extravasated red blood cells were present. Immunohistochemistry staining was performed and the atypical cells demonstrated diffuse positive staining for friend leukemia integration 1 transcription factor (FLI-1), erythroblastosis virus E26 transforming sequence-related gene (ERG)(Figure 5), CD31, and CD68. There was patchy positive staining for cytokeratin AE1/AE3, CD10, and factor VIII. There was no remarkable staining for human herpesvirus 8, epithelial membrane antigen, S-100, CD34, cytokeratin 903, and desmin. Overall, the histologic features in conjunction with the immunohistochemistry staining were consistent with a diagnosis of PMHE.

Magnetic resonance imaging was then performed to evaluate the depth and extent of the lesions for surgical excision planning (Figure 6), which showed 5 nodular lesions within the dermis and subcutis adjacent to the proximal aspect of the left tibia and medial aspect of the left knee. An additional lesion was noted between the sartorius and semimembranosus muscles, which was thought to represent either a lymph node or an additional neoplastic lesion. Chest computed tomography also displayed indeterminate lesions in the lungs.

Excision of the superficial lesions was performed. All of the lesions demonstrated similar histologic changes to the previously described biopsy specimen. The tumor was limited to the dermis and subcutaneous tissue. The patient was lost to follow-up and the etiology of the lung lesions was unknown.

Comment

Nomenclature
Pseudomyogenic hemangioendothelioma is a relatively new type of vascular tumor that has been included in the updated 2013 edition of the World Health Organization classification as an intermediate malignant tumor that rarely metastasizes.³ It typically involves multiple tissue planes, most notably the dermis and subcutaneous layers but also muscle and bone.⁴ The term pseudomyogenic refers to the histologic resemblance of some of the cells to rhabdomyoblasts; however, these tumors are negative for all immunohistochemical muscle markers, most notably myogenin, desmin, and α-smooth muscle actin.⁵

Clinical Presentation
Gross features of PMHE typically include multiple firm nodules with ill-defined margins. The tumor was initially described in 1992 by Mirra et al² as a fibromalike variant of epithelioid sarcoma. In 2003, a series of 7 cases of PMHE was reported by Billings et al⁶ under the term epithelioid sarcomalike hemangioendothelioma. Other than the predominance of an epithelioid morphology, the cases reported as epithelioid sarcomalike hemangioendothelioma had similar clinical features and immunophenotype to what has been reported as PMHE.

Based on a PubMed search of articles indexed for MEDLINE using the term pseudomyogenic hemangioendothelioma, the 2 largest case series were reported by Pradhan et al⁷ (N=8) in 2017 and Hornick and Fletcher⁴ (N=50) in 2011. Hornick and Fletcher⁴ reported a male (41/50 [82.0%]) to female (9/50 [18.0%]) ratio of 4.6 to 1, and an average age at presentation of 31 years with 82% (41/50) of patients 40 years or younger. Pradhan et al⁷ also reported a male predominance (7/8 [87.5%]) with a similar average age at presentation of 29 years (age range, 9–62 years). The size of individual tumors ranged from 0.3 to 5.5 cm (mean size, 1.9 cm) in the series by Hornick and Fletcher⁴ and 0.3 to 6.0 com in the series by Pradhan et al.⁷ Hornick and Fletcher⁴ reported the most common site of involvement was the leg (27/50 [54.0%]), followed by the arm (12/50 [24.0%]), trunk (9/50 [18.0%]), and head and neck (2/50 [4.0%]). The leg (6/8 [75.0%]) also was the most common site of involvement in the series by Pradhan et al,⁷ with 2 cases occurring on the arm. In the series by Hornick and Fletcher,⁴ the tumors typically involved the dermis and subcutaneous tissue (26/50 [52%]) with a smaller number involving skeletal muscle (17/50 [34%]) and bone (7/50 [14%]). They reported 66% of their patients (33/50) had multifocal disease at presentation.⁴ Pradhan et al⁷ also reported 2 (25.0%) cases being limited to the superficial soft tissue, 2 (25.0%) being limited to the deep soft tissue, and 4 (50.0%) involving the bone; 5 (62.5%) patients had multifocal disease at presentation. The presentation of our patient in regards to gender, age, and tumor characteristics is consistent with other published cases.^5-10

Histopathology
Microscopic features of PMHE include sheets of spindled to epithelioid-appearing cells with mild to moderate nuclear atypia and eosinophilic cytoplasm. The tumor has an infiltrative growth pattern. Some of the cells may resemble rhabdomyoblastlike cells, hence the moniker pseudomyogenic. There is no recapitulation of vascular structures or remarkable cytoplasmic vacuolization. Mitotic rate is low and there is no tumor necrosis.⁴ The tumor cells do not appear to arise from a vessel or display an angiocentric growth pattern. Many cases report the presence of an inflammatory infiltrate containing neutrophils interspersed within the tumor.^4,5,7 The overlying epidermis will commonly show hyperkeratosis, epidermal hyperplasia, and acanthosis.^4,11

Differential Diagnosis
The histopathologic differential diagnosis would include epithelioid sarcoma, epithelioid hemangioendothelioma, and to a lesser extent dermatofibrosarcoma protuberans (DFSP) and rhabdomyosarcoma. Dermatofibrosarcoma protuberans is the most commonly encountered of these tumors. Histologically, DFSP is characterized by a cellular proliferation of small spindle cells with plump nuclei arranged in a storiform or cartwheel pattern. Dermatofibrosarcoma protuberans tends to be limited to the dermis and subcutaneous tissue and only rarely involves underlying skeletal muscle. The presence of the storiform growth pattern in conjunction with the lack of rhabdoid changes would favor a diagnosis of DFSP. Another characteristic histologic finding typically only associated with DFSP is the interdigitating growth pattern of the spindle cells within the lobules of the subcutaneous tissue, creating a lacelike or honeycomb appearance.

Immunohistochemistry staining is necessary to help differentiate PMHE from other tumors in the differential diagnosis. Pseudomyogenic hemangioendothelioma stains positive for cytokeratin AE1/AE3; integrase interactor 1; and vascular markers FLI-1, CD31, and ERG, and negative for CD34.^4,6,12-15 In contrast to epithelioid hemangioendothelioma, DFSP, and to a lesser extent epithelioid sarcoma, all of which are positive for CD34, epithelioid sarcoma is negative for both CD31 and integrase interactor 1. Dermatofibrosarcoma protuberans is negative for cytokeratin AE1/AE3. Rhabdomyosarcomas are positive for myogenic markers such as MyoD1 and myogenin, unlike any of the other tumors mentioned. Histologically, epithelioid sarcomas will tend to have a granulomalike growth pattern with central necrosis, unlike PMHE.¹² Epithelioid hemangioendothelioma often will have a cordlike growth pattern in a myxochondroid background. Unlike PMHE, these tumors often will appear to be arising from vessels, and intracytoplasmic vacuoles are common. Three cases of PMHE have been reported to have a t(7;19)(q22;q13) chromosomal anomaly, which is not consistent with every case.¹⁶

Treatment Options
Standard treatment typically includes wide excision of the lesions, as was done in our case. Because of the substantial risk of local recurrence, which was up to 58% in the series by Hornick and Fletcher,⁴ adjuvant therapy may be considered if positive margins are found on excision. Metastasis to lymph nodes and the lungs has been reported but is rare.^2,4 Most cases have been shown to have a favorable prognosis; however, local recurrence seems to be common. Rarely, amputation of the limb may be required.⁵ In contrast, epithelioid sarcomas have been found to spread to lymph nodes and the lungs in up to 50% of cases with a 5-year survival rate of 10% to 30%.¹³

Conclusion

In summary, we describe a case of PMHE involving the lower leg in a 20-year-old man. These tumors often are multinodular and multiplanar, with the dermis and subcutaneous tissues being the most common areas affected. It has a high rate of local recurrence but rarely has distant metastasis. Pseudomyogenic hemangioendothelioma, similar to other soft tissue tumors, can be difficult to diagnose on shave biopsy or superficial punch biopsy not extending into subcutaneous tissue. Deep incisional or punch biopsies are required to more definitively diagnose these types of tumors. The diagnosis of PMHE versus other soft tissue tumors requires correlation of histology and immunohistochemistry staining with clinical information and radiographic findings.

Among rural adults, multiple chronic health conditions are most common in non-Hispanic blacks and American Indians/Alaska Natives (AI/ANs) and least common among Asians and Native Hawaiians/other Pacific Islanders (NHOPIs), according to the Centers for Disease Control and Prevention.

rfranki@frontlinemedcom.com

Among rural adults, multiple chronic health conditions are most common in non-Hispanic blacks and American Indians/Alaska Natives (AI/ANs) and least common among Asians and Native Hawaiians/other Pacific Islanders (NHOPIs), according to the Centers for Disease Control and Prevention.

rfranki@frontlinemedcom.com

Among rural adults, multiple chronic health conditions are most common in non-Hispanic blacks and American Indians/Alaska Natives (AI/ANs) and least common among Asians and Native Hawaiians/other Pacific Islanders (NHOPIs), according to the Centers for Disease Control and Prevention.

rfranki@frontlinemedcom.com

Parents generally can take photographs of good enough quality to allow accurate teledermatology diagnoses to be made of many pediatric skin conditions, said Daniel M. O’Connor, MD, of the Children’s Hospital of Philadelphia, and his associates.

Skin conditions make up 10%-30% of the approximately 200 million pediatric outpatient visits each year, Dr. O’Connor and his colleagues said. But there are fewer than 300 board-certified U.S. pediatric dermatologists for the nation’s nearly 75 million children. So, the possibility of using photos taken by parents for distant pediatric dermatologists to assess is an attractive one.

copyright/Thinkstock.com

Parents generally can take photographs of good enough quality to allow accurate teledermatology diagnoses to be made of many pediatric skin conditions, said Daniel M. O’Connor, MD, of the Children’s Hospital of Philadelphia, and his associates.

Skin conditions make up 10%-30% of the approximately 200 million pediatric outpatient visits each year, Dr. O’Connor and his colleagues said. But there are fewer than 300 board-certified U.S. pediatric dermatologists for the nation’s nearly 75 million children. So, the possibility of using photos taken by parents for distant pediatric dermatologists to assess is an attractive one.

copyright/Thinkstock.com

Parents generally can take photographs of good enough quality to allow accurate teledermatology diagnoses to be made of many pediatric skin conditions, said Daniel M. O’Connor, MD, of the Children’s Hospital of Philadelphia, and his associates.

Skin conditions make up 10%-30% of the approximately 200 million pediatric outpatient visits each year, Dr. O’Connor and his colleagues said. But there are fewer than 300 board-certified U.S. pediatric dermatologists for the nation’s nearly 75 million children. So, the possibility of using photos taken by parents for distant pediatric dermatologists to assess is an attractive one.

copyright/Thinkstock.com

What is the recent research behind 5-fluorouracil cream 5% combined with calcipotriol ointment 0.005% for actinic keratoses?

Cunningham et al published a randomized double-blind study in which 131 patients with actinic keratoses (AKs) were assigned to either 5-fluorouracil (5-FU) cream 5% combined with calcipotriol (calcipotriene) ointment 0.005% twice daily to the face, scalp, and arms for 4 days, or 5-FU 5% combined with petrolatum applied in the same fashion. There was an 87.8% versus 26.3% mean reduction in the number of AKs and less severe pain, crusting, and ulceration in the study cohort compared to the 5-FU plus petrolatum group.

The same study also investigated immune parameters in these patients and found that the study group preferentially displayed activated thymic stromal lymphopoietin and a CD4 T cell-mediated reaction, among other effects. In prior studies, thymic stromal lymphopoietin has been shown to be upregulated in barrier-defective skin, displays antitumor activity, and is enhanced by topical calcipotriol application based on its original indication for psoriasis.

How do these study results impact patient care?

In a perfect world, every patient could tolerate and afford chemopreventative measures such as 5-FU cream, apply it diffusely to sun-exposed skin, and experience no severe irritant reactions and/or social pariah status. We all know that this product is effective, and we all overprepare patients to use it, knowing that they will call our offices panicked and fearful that they are allergic to or are becoming infected by this cream.

Although further study clearly is needed to determine the optimal application amount, duration of use, and vehicle mix, this new compound utilizing 2 topicals that are familiar to us--5-FU cream approved for AKs and early squamous cell skin cancers and calcipotriol ointment (though available only in cream in the United States currently) for psoriasis--is an encouraging step. Home therapy for AKs and possibly early nonmelanoma skin cancers that is more tolerable, of shorter duration, and in turn more effective than the current options would lessen the burden of treating these lesions surgically or rescheduling 5-FU patients often for irritation reaction education.

How do patients respond to this regimen?

In my own anecdotal experience, this regimen has been well received by patients and often is covered by most insurances when written as 2 separate prescriptions (both in cream vehicle).  They still report some irritation, but I prefer to utilize it segmentally instead of treating all sun-exposed areas at once (ie, treat one side of the face/scalp twice daily for 4 days, then the other, or even divide it into smaller segments once the prior segment has healed). This combination, in addition to, for example, adding nicotinamide 500 mg twice daily to a patient's skin cancer chemopreventative sequence, is in my opinion a novel but safe, effective, and well-tolerated field therapy recommendation.

Suggested Readings

• Cunningham TJ, Tabacchi M, Eliane JP, et al. Randomized trial of calcipotriol combined with 5-fluorouracil for skin cancer precursor immunotherapy. J Clin Invest. 2017;127:106-116.
• Demehri S, Turkoz A, Manivasagam S, et al. Elevated epidermal thymic stromal lymphopoietin levels establish an antitumor environment in the skin. Cancer Cell. 2012;22:494-505.
• Rosamilia LL. Three Cheers for B₃? Cutis. July 7, 2015. http://www.mdedge.com/cutis/article/101102/nonmelanoma-skin-cancer/three-cheers-b3. Accessed November 20, 2017.
• Sato-Deguchi E, Imafuku S, Chou B, et al. Topical vitamin D(3) analogues induce thymic stromal lymphopoietin and cathelicidin in psoriatic skin lesions. Br J Dermatol. 2012;167:77-84.

What is the recent research behind 5-fluorouracil cream 5% combined with calcipotriol ointment 0.005% for actinic keratoses?

Cunningham et al published a randomized double-blind study in which 131 patients with actinic keratoses (AKs) were assigned to either 5-fluorouracil (5-FU) cream 5% combined with calcipotriol (calcipotriene) ointment 0.005% twice daily to the face, scalp, and arms for 4 days, or 5-FU 5% combined with petrolatum applied in the same fashion. There was an 87.8% versus 26.3% mean reduction in the number of AKs and less severe pain, crusting, and ulceration in the study cohort compared to the 5-FU plus petrolatum group.

The same study also investigated immune parameters in these patients and found that the study group preferentially displayed activated thymic stromal lymphopoietin and a CD4 T cell-mediated reaction, among other effects. In prior studies, thymic stromal lymphopoietin has been shown to be upregulated in barrier-defective skin, displays antitumor activity, and is enhanced by topical calcipotriol application based on its original indication for psoriasis.

How do these study results impact patient care?

In a perfect world, every patient could tolerate and afford chemopreventative measures such as 5-FU cream, apply it diffusely to sun-exposed skin, and experience no severe irritant reactions and/or social pariah status. We all know that this product is effective, and we all overprepare patients to use it, knowing that they will call our offices panicked and fearful that they are allergic to or are becoming infected by this cream.

Although further study clearly is needed to determine the optimal application amount, duration of use, and vehicle mix, this new compound utilizing 2 topicals that are familiar to us--5-FU cream approved for AKs and early squamous cell skin cancers and calcipotriol ointment (though available only in cream in the United States currently) for psoriasis--is an encouraging step. Home therapy for AKs and possibly early nonmelanoma skin cancers that is more tolerable, of shorter duration, and in turn more effective than the current options would lessen the burden of treating these lesions surgically or rescheduling 5-FU patients often for irritation reaction education.

How do patients respond to this regimen?

In my own anecdotal experience, this regimen has been well received by patients and often is covered by most insurances when written as 2 separate prescriptions (both in cream vehicle).  They still report some irritation, but I prefer to utilize it segmentally instead of treating all sun-exposed areas at once (ie, treat one side of the face/scalp twice daily for 4 days, then the other, or even divide it into smaller segments once the prior segment has healed). This combination, in addition to, for example, adding nicotinamide 500 mg twice daily to a patient's skin cancer chemopreventative sequence, is in my opinion a novel but safe, effective, and well-tolerated field therapy recommendation.

Suggested Readings

• Cunningham TJ, Tabacchi M, Eliane JP, et al. Randomized trial of calcipotriol combined with 5-fluorouracil for skin cancer precursor immunotherapy. J Clin Invest. 2017;127:106-116.
• Demehri S, Turkoz A, Manivasagam S, et al. Elevated epidermal thymic stromal lymphopoietin levels establish an antitumor environment in the skin. Cancer Cell. 2012;22:494-505.
• Rosamilia LL. Three Cheers for B₃? Cutis. July 7, 2015. http://www.mdedge.com/cutis/article/101102/nonmelanoma-skin-cancer/three-cheers-b3. Accessed November 20, 2017.
• Sato-Deguchi E, Imafuku S, Chou B, et al. Topical vitamin D(3) analogues induce thymic stromal lymphopoietin and cathelicidin in psoriatic skin lesions. Br J Dermatol. 2012;167:77-84.

What is the recent research behind 5-fluorouracil cream 5% combined with calcipotriol ointment 0.005% for actinic keratoses?

Cunningham et al published a randomized double-blind study in which 131 patients with actinic keratoses (AKs) were assigned to either 5-fluorouracil (5-FU) cream 5% combined with calcipotriol (calcipotriene) ointment 0.005% twice daily to the face, scalp, and arms for 4 days, or 5-FU 5% combined with petrolatum applied in the same fashion. There was an 87.8% versus 26.3% mean reduction in the number of AKs and less severe pain, crusting, and ulceration in the study cohort compared to the 5-FU plus petrolatum group.

The same study also investigated immune parameters in these patients and found that the study group preferentially displayed activated thymic stromal lymphopoietin and a CD4 T cell-mediated reaction, among other effects. In prior studies, thymic stromal lymphopoietin has been shown to be upregulated in barrier-defective skin, displays antitumor activity, and is enhanced by topical calcipotriol application based on its original indication for psoriasis.

How do these study results impact patient care?

In a perfect world, every patient could tolerate and afford chemopreventative measures such as 5-FU cream, apply it diffusely to sun-exposed skin, and experience no severe irritant reactions and/or social pariah status. We all know that this product is effective, and we all overprepare patients to use it, knowing that they will call our offices panicked and fearful that they are allergic to or are becoming infected by this cream.

Although further study clearly is needed to determine the optimal application amount, duration of use, and vehicle mix, this new compound utilizing 2 topicals that are familiar to us--5-FU cream approved for AKs and early squamous cell skin cancers and calcipotriol ointment (though available only in cream in the United States currently) for psoriasis--is an encouraging step. Home therapy for AKs and possibly early nonmelanoma skin cancers that is more tolerable, of shorter duration, and in turn more effective than the current options would lessen the burden of treating these lesions surgically or rescheduling 5-FU patients often for irritation reaction education.

How do patients respond to this regimen?

In my own anecdotal experience, this regimen has been well received by patients and often is covered by most insurances when written as 2 separate prescriptions (both in cream vehicle).  They still report some irritation, but I prefer to utilize it segmentally instead of treating all sun-exposed areas at once (ie, treat one side of the face/scalp twice daily for 4 days, then the other, or even divide it into smaller segments once the prior segment has healed). This combination, in addition to, for example, adding nicotinamide 500 mg twice daily to a patient's skin cancer chemopreventative sequence, is in my opinion a novel but safe, effective, and well-tolerated field therapy recommendation.

Suggested Readings

• Cunningham TJ, Tabacchi M, Eliane JP, et al. Randomized trial of calcipotriol combined with 5-fluorouracil for skin cancer precursor immunotherapy. J Clin Invest. 2017;127:106-116.
• Demehri S, Turkoz A, Manivasagam S, et al. Elevated epidermal thymic stromal lymphopoietin levels establish an antitumor environment in the skin. Cancer Cell. 2012;22:494-505.
• Rosamilia LL. Three Cheers for B₃? Cutis. July 7, 2015. http://www.mdedge.com/cutis/article/101102/nonmelanoma-skin-cancer/three-cheers-b3. Accessed November 20, 2017.
• Sato-Deguchi E, Imafuku S, Chou B, et al. Topical vitamin D(3) analogues induce thymic stromal lymphopoietin and cathelicidin in psoriatic skin lesions. Br J Dermatol. 2012;167:77-84.

Coastal travel accounts for 80% of all tourism worldwide, a number that continues to grow. The number of travelers to the Mediterranean Sea alone is expected to rise to 350 million individuals per year within the next 20 years.¹ As the number of tourists visiting the world’s oceans increases, the rate of sunscreen unintentionally washed into these marine environments also rises. One study estimated that approximately one-quarter of the sunscreen applied to the skin is washed off over a 20-minute period spent in the water.² Four of the most common sunscreen agents—benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), and the nanoparticles titanium dioxide and zinc oxide—have been considered to be risks to marine environments. As this topic has received increasing media scrutiny over the last few years, we summarize the general conclusions that can be drawn from current research and note the questions that still remain to better address patient concerns.

Benzophenone-3

Benzophenone-3, or oxybenzone, is a widely studied UV filter and its effects on marine ecosystems have received the media’s attention over the last few years. Benzophenone-3 is known to cause a bleaching effect to coral, which can inhibit growth and possibly kill the organism.³ Further, oxybenzone sunscreens can promote viral infections in coral, resulting in additional bleaching events.² In a recent study, exposure to BP-3 caused mobile planulae, the larval form of coral, to become clearly deformed, trapped within its own calcium carbonate skeleton.³ The concentration of BP-3 needed to induce these physiological changes is as small as 62 parts per trillion, which is the equivalent of a single drop of water in 6.5 Olympic-sized swimming pools. Levels of BP-3 contamination in the waters off of the US Virgin Islands’ beaches have been recorded as high as 1.4 parts per million, with average concentrations closer to 250 parts per billion.³ High BP-3 concentrations have also been recorded in the waters off the Canary Islands,⁴ Hawaii,³ and South Carolina.⁵

4-Methylbenzylidene Camphor

Environmental concerns have also been raised about another common chemical UV filter: 4-MBC, or enzacamene. In laboratory studies, 4-MBC has been shown to cause oxidative stress to Tetrahymena thermophila, an aquatic protozoan, which results in inhibited growth. At higher concentrations, damage to the cellular membrane was seen as soon as 4 hours after exposure.⁶ In embryonic zebrafish, elevated 4-MBC levels were correlated to improper nerve and muscular development, resulting in developmental defects.⁷ Another study demonstrated that 4-MBC was toxic to Mytilus galloprovincialis, known as the Mediterranean mussel, and Paracentrotus lividus, a species of sea urchin.⁸ Although these studies utilized highly controlled laboratory settings, further studies are needed to examine the effects of 4-MBC on these species at environmentally relevant concentrations.

Physical Sunscreens

Physical sunscreens, as compared to the chemical filters referenced above, use either zinc or titanium to protect the skin from the sun’s rays. Nanoparticles, in particular, are preferred because they do not leave a white film on the skin.⁹ Both titanium dioxide and zinc oxide nanoparticles have been found to inhibit the growth and photosynthesis of marine phytoplankton, the most abundant primary producers on Earth.^10,11 These metal contaminants can be transferred to organisms of higher trophic levels, including zooplankton,¹² and filter-feeding organisms, including marine abalone¹³ and the Mediterranean mussel.¹⁴ These nanoparticles have been shown to cause oxidative stress to these organisms, making them less fit to withstand environmental stressors. It is difficult to show their true impact, however, as it is challenging to accurately detect and quantify nanoparticle concentrations in vivo.¹⁵

Final Thoughts

A recent study showed that 7% of consumers (N=325) regarded environmental agencies’ recommendations as an important factor in their sunscreen purchase.¹⁶ When treating patients with these concerns, the ability to provide sound and informed advice will likely impact their sunscreen use and future sun protection behaviors. Although studies have shown the potential for sunscreen pollution to cause environmental harm, it is important to note that a portion of this research is not correlated to in vivo findings, and further work is required to determine the magnitude and importance of these studies.¹⁵ Regardless, legislation has already been submitted in both Hawaii and the European Union calling for a ban on oxybenzone-containing sunscreens, so knowledge of the subject is prudent when counseling patients.¹⁷ One potential solution may be to recommend sun-protective clothing during water-intensive activities to both increase skin protection and reduce the environmental impact. Furthermore, recommendations could be tailored to specific settings, such as coastal resorts and populated beaches, where these sunscreen ingredients are found in much higher concentrations. At this time, more data must be collected before making any definitive claims or recommendations, but knowledge of the current research will be an important tool in educating patients going forward.

Coastal travel accounts for 80% of all tourism worldwide, a number that continues to grow. The number of travelers to the Mediterranean Sea alone is expected to rise to 350 million individuals per year within the next 20 years.¹ As the number of tourists visiting the world’s oceans increases, the rate of sunscreen unintentionally washed into these marine environments also rises. One study estimated that approximately one-quarter of the sunscreen applied to the skin is washed off over a 20-minute period spent in the water.² Four of the most common sunscreen agents—benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), and the nanoparticles titanium dioxide and zinc oxide—have been considered to be risks to marine environments. As this topic has received increasing media scrutiny over the last few years, we summarize the general conclusions that can be drawn from current research and note the questions that still remain to better address patient concerns.

Benzophenone-3

Benzophenone-3, or oxybenzone, is a widely studied UV filter and its effects on marine ecosystems have received the media’s attention over the last few years. Benzophenone-3 is known to cause a bleaching effect to coral, which can inhibit growth and possibly kill the organism.³ Further, oxybenzone sunscreens can promote viral infections in coral, resulting in additional bleaching events.² In a recent study, exposure to BP-3 caused mobile planulae, the larval form of coral, to become clearly deformed, trapped within its own calcium carbonate skeleton.³ The concentration of BP-3 needed to induce these physiological changes is as small as 62 parts per trillion, which is the equivalent of a single drop of water in 6.5 Olympic-sized swimming pools. Levels of BP-3 contamination in the waters off of the US Virgin Islands’ beaches have been recorded as high as 1.4 parts per million, with average concentrations closer to 250 parts per billion.³ High BP-3 concentrations have also been recorded in the waters off the Canary Islands,⁴ Hawaii,³ and South Carolina.⁵

4-Methylbenzylidene Camphor

Environmental concerns have also been raised about another common chemical UV filter: 4-MBC, or enzacamene. In laboratory studies, 4-MBC has been shown to cause oxidative stress to Tetrahymena thermophila, an aquatic protozoan, which results in inhibited growth. At higher concentrations, damage to the cellular membrane was seen as soon as 4 hours after exposure.⁶ In embryonic zebrafish, elevated 4-MBC levels were correlated to improper nerve and muscular development, resulting in developmental defects.⁷ Another study demonstrated that 4-MBC was toxic to Mytilus galloprovincialis, known as the Mediterranean mussel, and Paracentrotus lividus, a species of sea urchin.⁸ Although these studies utilized highly controlled laboratory settings, further studies are needed to examine the effects of 4-MBC on these species at environmentally relevant concentrations.

Physical Sunscreens

Physical sunscreens, as compared to the chemical filters referenced above, use either zinc or titanium to protect the skin from the sun’s rays. Nanoparticles, in particular, are preferred because they do not leave a white film on the skin.⁹ Both titanium dioxide and zinc oxide nanoparticles have been found to inhibit the growth and photosynthesis of marine phytoplankton, the most abundant primary producers on Earth.^10,11 These metal contaminants can be transferred to organisms of higher trophic levels, including zooplankton,¹² and filter-feeding organisms, including marine abalone¹³ and the Mediterranean mussel.¹⁴ These nanoparticles have been shown to cause oxidative stress to these organisms, making them less fit to withstand environmental stressors. It is difficult to show their true impact, however, as it is challenging to accurately detect and quantify nanoparticle concentrations in vivo.¹⁵

Final Thoughts

A recent study showed that 7% of consumers (N=325) regarded environmental agencies’ recommendations as an important factor in their sunscreen purchase.¹⁶ When treating patients with these concerns, the ability to provide sound and informed advice will likely impact their sunscreen use and future sun protection behaviors. Although studies have shown the potential for sunscreen pollution to cause environmental harm, it is important to note that a portion of this research is not correlated to in vivo findings, and further work is required to determine the magnitude and importance of these studies.¹⁵ Regardless, legislation has already been submitted in both Hawaii and the European Union calling for a ban on oxybenzone-containing sunscreens, so knowledge of the subject is prudent when counseling patients.¹⁷ One potential solution may be to recommend sun-protective clothing during water-intensive activities to both increase skin protection and reduce the environmental impact. Furthermore, recommendations could be tailored to specific settings, such as coastal resorts and populated beaches, where these sunscreen ingredients are found in much higher concentrations. At this time, more data must be collected before making any definitive claims or recommendations, but knowledge of the current research will be an important tool in educating patients going forward.

Coastal travel accounts for 80% of all tourism worldwide, a number that continues to grow. The number of travelers to the Mediterranean Sea alone is expected to rise to 350 million individuals per year within the next 20 years.¹ As the number of tourists visiting the world’s oceans increases, the rate of sunscreen unintentionally washed into these marine environments also rises. One study estimated that approximately one-quarter of the sunscreen applied to the skin is washed off over a 20-minute period spent in the water.² Four of the most common sunscreen agents—benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), and the nanoparticles titanium dioxide and zinc oxide—have been considered to be risks to marine environments. As this topic has received increasing media scrutiny over the last few years, we summarize the general conclusions that can be drawn from current research and note the questions that still remain to better address patient concerns.

Benzophenone-3

Benzophenone-3, or oxybenzone, is a widely studied UV filter and its effects on marine ecosystems have received the media’s attention over the last few years. Benzophenone-3 is known to cause a bleaching effect to coral, which can inhibit growth and possibly kill the organism.³ Further, oxybenzone sunscreens can promote viral infections in coral, resulting in additional bleaching events.² In a recent study, exposure to BP-3 caused mobile planulae, the larval form of coral, to become clearly deformed, trapped within its own calcium carbonate skeleton.³ The concentration of BP-3 needed to induce these physiological changes is as small as 62 parts per trillion, which is the equivalent of a single drop of water in 6.5 Olympic-sized swimming pools. Levels of BP-3 contamination in the waters off of the US Virgin Islands’ beaches have been recorded as high as 1.4 parts per million, with average concentrations closer to 250 parts per billion.³ High BP-3 concentrations have also been recorded in the waters off the Canary Islands,⁴ Hawaii,³ and South Carolina.⁵

4-Methylbenzylidene Camphor

Environmental concerns have also been raised about another common chemical UV filter: 4-MBC, or enzacamene. In laboratory studies, 4-MBC has been shown to cause oxidative stress to Tetrahymena thermophila, an aquatic protozoan, which results in inhibited growth. At higher concentrations, damage to the cellular membrane was seen as soon as 4 hours after exposure.⁶ In embryonic zebrafish, elevated 4-MBC levels were correlated to improper nerve and muscular development, resulting in developmental defects.⁷ Another study demonstrated that 4-MBC was toxic to Mytilus galloprovincialis, known as the Mediterranean mussel, and Paracentrotus lividus, a species of sea urchin.⁸ Although these studies utilized highly controlled laboratory settings, further studies are needed to examine the effects of 4-MBC on these species at environmentally relevant concentrations.

Physical Sunscreens

Physical sunscreens, as compared to the chemical filters referenced above, use either zinc or titanium to protect the skin from the sun’s rays. Nanoparticles, in particular, are preferred because they do not leave a white film on the skin.⁹ Both titanium dioxide and zinc oxide nanoparticles have been found to inhibit the growth and photosynthesis of marine phytoplankton, the most abundant primary producers on Earth.^10,11 These metal contaminants can be transferred to organisms of higher trophic levels, including zooplankton,¹² and filter-feeding organisms, including marine abalone¹³ and the Mediterranean mussel.¹⁴ These nanoparticles have been shown to cause oxidative stress to these organisms, making them less fit to withstand environmental stressors. It is difficult to show their true impact, however, as it is challenging to accurately detect and quantify nanoparticle concentrations in vivo.¹⁵

Final Thoughts

A recent study showed that 7% of consumers (N=325) regarded environmental agencies’ recommendations as an important factor in their sunscreen purchase.¹⁶ When treating patients with these concerns, the ability to provide sound and informed advice will likely impact their sunscreen use and future sun protection behaviors. Although studies have shown the potential for sunscreen pollution to cause environmental harm, it is important to note that a portion of this research is not correlated to in vivo findings, and further work is required to determine the magnitude and importance of these studies.¹⁵ Regardless, legislation has already been submitted in both Hawaii and the European Union calling for a ban on oxybenzone-containing sunscreens, so knowledge of the subject is prudent when counseling patients.¹⁷ One potential solution may be to recommend sun-protective clothing during water-intensive activities to both increase skin protection and reduce the environmental impact. Furthermore, recommendations could be tailored to specific settings, such as coastal resorts and populated beaches, where these sunscreen ingredients are found in much higher concentrations. At this time, more data must be collected before making any definitive claims or recommendations, but knowledge of the current research will be an important tool in educating patients going forward.

The Diagnosis: Primary Cutaneous Follicle Center Lymphoma

Immunohistochemistry revealed a nodular infiltrate consisting of small to large atypical lymphocytes forming an irregular germinal center with notably thinned mantle zones and lack of polarization (Figure, A). Atypical cells stained positively with Bcl-6, and CD20 was diffusely positive (Figure, B-D). Bcl-2 and CD3 colocalized to the reactive T-cell infiltrate, and CD10 was largely negative. Further workup with bone marrow biopsy and full-body positron emission tomography-computed tomography was unremarkable. Given these findings, a diagnosis of primary cutaneous follicle center lymphoma (FCL) was made. At 1 month following radiation therapy, complete clinical clearance of the lymphoma was achieved.

Follicle center lymphoma, also known as cutaneous follicular lymphoma, is the most common subtype of primary cutaneous B-cell lymphomas, representing approximately 57% of cases.¹ Follicle center lymphoma typically affects older, non-Hispanic white adults with a median age of onset of 60 years. It has a predilection for the head, neck, and trunk.² Lesions present as solitary erythematous to violaceous papules, plaques, or nodules, but they can more rarely be multifocal.³ Clinical diagnosis of FCL can be difficult, with papular lesions resembling acne, rosacea, folliculitis, or arthropod assault.^4,5 As such, diagnosis of FCL typically relies on histopathologic analysis.

Histologically, FCL can present in several different patterns including follicular, nodular, diffuse, or a pleomorphic mix of these.^2,6 The cells are comprised of germinal center B cells, staining positively for Bcl-6, CD20, and CD79a.⁷ Tumor cells do not exhibit the t(14;18) translocation seen in nodal follicular lymphomas.^2,8 Unlike marginal zone lymphoma, FCL stains negatively for Bcl-2 and multiple myeloma 1/interferon regulatory factor 4 (MUM1/IRF-4).^2,9 Forkhead box P1 (FOXP1) also is usually negative, but its presence can indicate a poorer prognosis.² It is important to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphoma with secondary cutaneous involvement, as they have a different clinical prognosis and management course. Further workup includes bone marrow biopsy, serum analysis for clonal involvement, and positron emission tomography-computed tomography imaging. Follicle center lymphoma generally has an indolent disease course with a favorable 5-year survival rate of approximately 95%.^6,8

Untreated lesions may enlarge slowly or even spontaneously involute.¹⁰ The histologic growth pattern and number of lesions do not affect prognosis, but presence on the legs has a 5-year survival rate of 41%.² Extracutaneous dissemination can occur in 5% to 10% of cases.² Given the slow progression of FCL, conservative management with observation is an option. However, curative treatment can be reasonably attempted for solitary lesions by excision or radiation. Treatment of FCL often can be complicated by its predilection for the head and neck. Other treatment modalities include topical steroids, imiquimod, nitrogen mustard, and bexarotene.¹⁰ More generalized involvement may require systemic therapy with rituximab or chemotherapy. Recurrence after therapy is common, reported in 46.5% of patients, but does not affect prognosis.²

The Diagnosis: Primary Cutaneous Follicle Center Lymphoma

Immunohistochemistry revealed a nodular infiltrate consisting of small to large atypical lymphocytes forming an irregular germinal center with notably thinned mantle zones and lack of polarization (Figure, A). Atypical cells stained positively with Bcl-6, and CD20 was diffusely positive (Figure, B-D). Bcl-2 and CD3 colocalized to the reactive T-cell infiltrate, and CD10 was largely negative. Further workup with bone marrow biopsy and full-body positron emission tomography-computed tomography was unremarkable. Given these findings, a diagnosis of primary cutaneous follicle center lymphoma (FCL) was made. At 1 month following radiation therapy, complete clinical clearance of the lymphoma was achieved.

Follicle center lymphoma, also known as cutaneous follicular lymphoma, is the most common subtype of primary cutaneous B-cell lymphomas, representing approximately 57% of cases.¹ Follicle center lymphoma typically affects older, non-Hispanic white adults with a median age of onset of 60 years. It has a predilection for the head, neck, and trunk.² Lesions present as solitary erythematous to violaceous papules, plaques, or nodules, but they can more rarely be multifocal.³ Clinical diagnosis of FCL can be difficult, with papular lesions resembling acne, rosacea, folliculitis, or arthropod assault.^4,5 As such, diagnosis of FCL typically relies on histopathologic analysis.

Histologically, FCL can present in several different patterns including follicular, nodular, diffuse, or a pleomorphic mix of these.^2,6 The cells are comprised of germinal center B cells, staining positively for Bcl-6, CD20, and CD79a.⁷ Tumor cells do not exhibit the t(14;18) translocation seen in nodal follicular lymphomas.^2,8 Unlike marginal zone lymphoma, FCL stains negatively for Bcl-2 and multiple myeloma 1/interferon regulatory factor 4 (MUM1/IRF-4).^2,9 Forkhead box P1 (FOXP1) also is usually negative, but its presence can indicate a poorer prognosis.² It is important to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphoma with secondary cutaneous involvement, as they have a different clinical prognosis and management course. Further workup includes bone marrow biopsy, serum analysis for clonal involvement, and positron emission tomography-computed tomography imaging. Follicle center lymphoma generally has an indolent disease course with a favorable 5-year survival rate of approximately 95%.^6,8

Untreated lesions may enlarge slowly or even spontaneously involute.¹⁰ The histologic growth pattern and number of lesions do not affect prognosis, but presence on the legs has a 5-year survival rate of 41%.² Extracutaneous dissemination can occur in 5% to 10% of cases.² Given the slow progression of FCL, conservative management with observation is an option. However, curative treatment can be reasonably attempted for solitary lesions by excision or radiation. Treatment of FCL often can be complicated by its predilection for the head and neck. Other treatment modalities include topical steroids, imiquimod, nitrogen mustard, and bexarotene.¹⁰ More generalized involvement may require systemic therapy with rituximab or chemotherapy. Recurrence after therapy is common, reported in 46.5% of patients, but does not affect prognosis.²

The Diagnosis: Primary Cutaneous Follicle Center Lymphoma

Immunohistochemistry revealed a nodular infiltrate consisting of small to large atypical lymphocytes forming an irregular germinal center with notably thinned mantle zones and lack of polarization (Figure, A). Atypical cells stained positively with Bcl-6, and CD20 was diffusely positive (Figure, B-D). Bcl-2 and CD3 colocalized to the reactive T-cell infiltrate, and CD10 was largely negative. Further workup with bone marrow biopsy and full-body positron emission tomography-computed tomography was unremarkable. Given these findings, a diagnosis of primary cutaneous follicle center lymphoma (FCL) was made. At 1 month following radiation therapy, complete clinical clearance of the lymphoma was achieved.

Follicle center lymphoma, also known as cutaneous follicular lymphoma, is the most common subtype of primary cutaneous B-cell lymphomas, representing approximately 57% of cases.¹ Follicle center lymphoma typically affects older, non-Hispanic white adults with a median age of onset of 60 years. It has a predilection for the head, neck, and trunk.² Lesions present as solitary erythematous to violaceous papules, plaques, or nodules, but they can more rarely be multifocal.³ Clinical diagnosis of FCL can be difficult, with papular lesions resembling acne, rosacea, folliculitis, or arthropod assault.^4,5 As such, diagnosis of FCL typically relies on histopathologic analysis.

Histologically, FCL can present in several different patterns including follicular, nodular, diffuse, or a pleomorphic mix of these.^2,6 The cells are comprised of germinal center B cells, staining positively for Bcl-6, CD20, and CD79a.⁷ Tumor cells do not exhibit the t(14;18) translocation seen in nodal follicular lymphomas.^2,8 Unlike marginal zone lymphoma, FCL stains negatively for Bcl-2 and multiple myeloma 1/interferon regulatory factor 4 (MUM1/IRF-4).^2,9 Forkhead box P1 (FOXP1) also is usually negative, but its presence can indicate a poorer prognosis.² It is important to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphoma with secondary cutaneous involvement, as they have a different clinical prognosis and management course. Further workup includes bone marrow biopsy, serum analysis for clonal involvement, and positron emission tomography-computed tomography imaging. Follicle center lymphoma generally has an indolent disease course with a favorable 5-year survival rate of approximately 95%.^6,8

Untreated lesions may enlarge slowly or even spontaneously involute.¹⁰ The histologic growth pattern and number of lesions do not affect prognosis, but presence on the legs has a 5-year survival rate of 41%.² Extracutaneous dissemination can occur in 5% to 10% of cases.² Given the slow progression of FCL, conservative management with observation is an option. However, curative treatment can be reasonably attempted for solitary lesions by excision or radiation. Treatment of FCL often can be complicated by its predilection for the head and neck. Other treatment modalities include topical steroids, imiquimod, nitrogen mustard, and bexarotene.¹⁰ More generalized involvement may require systemic therapy with rituximab or chemotherapy. Recurrence after therapy is common, reported in 46.5% of patients, but does not affect prognosis.²

Lesions of porokeratosis are thought to arise from disordered keratinization, though the exact pathogenesis remains uncertain. At least 5 clinical subtypes of porokeratosis have been identified: porokeratosis of Mibelli, disseminated superficial porokeratosis and disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, punctuate porokeratosis, and porokeratosis palmaris et plantaris disseminata (PPPD).^1,2 Linear porokeratosis is a rare subtype with a clinical differential diagnosis that includes lichen striatus, linear lichen planus, linear verrucous epidermal nevus, segmental Darier disease, and incontinentia pigmenti.³ Definitive diagnosis of linear porokeratosis is made by histopathologic examination demonstrating a cornoid lamella, defined as a column of parakeratotic cells that lies at 45°to the surface of the epidermis and contains pyknotic basophilic nuclei.⁴ Patients with linear porokeratosis typically develop lesions along the lines of Blaschko in infancy or childhood.^5,6 Among the different subtypes of porokeratosis, linear porokeratosis demonstrates the highest rate of malignant transformation, therefore requiring close clinical observation.⁷

Case Report

An 83-year-old woman presented to the outpatient clinic with a large linear plaque on the right leg that had been present since birth. Ten years prior to presentation, a portion of the lesion started to bleed; biopsy of the area was performed by an outside provider demonstrating squamous cell carcinoma (SCC), which was treated with wide local excision. One year prior to presentation, a separate portion of the plaque was biopsied by an outside provider and another diagnosis of SCC was made.

On examination performed during the initial presentation to our clinic, there was a well-demarcated tan to violaceous linear plaque present at the lower buttock and extending along the posterior leg to the skin overlying the Achilles tendon and dorsal aspect of the right foot. Within the plaque, there were areas of atrophy and areas of inflammation, induration, and hyperkeratosis (Figures 1 and 2). Two punch biopsies were performed: one from the edge of the plaque and one from a hyperkeratotic region within the plaque. Histology from the edge of the plaque demonstrated a cornoid lamella, consistent with a porokeratosis (Figure 3), whereas the histology from the hyperkeratotic region demonstrated a lichenoid infiltrate (Figure 4).

Several treatment options directed at the entire lesion were offered to the patient, but she declined these therapies and opted to address only those areas with clinical features of SCC, such as hyperkeratosis, bleeding, and rapid growth. Although biopsies performed by an outside provider were consistent with SCC, it had not been detected on biopsy performed during her initial visit to our clinic.

The patient was educated on the risk associated with her condition and instructed to follow up every 6 months to monitor for the development of SCC.

Comment

Porokeratosis is a disorder of keratinization with at least 5 clinical subtypes that share histologic similarities: porokeratosis of Mibelli, disseminated superficial porokeratosis and DSAP, linear porokeratosis, punctate porokeratosis, and PPPD.^1,2 Other less common variants of porokeratosis include porokeratosis ptychotropica (a verrucous variant confined to the perianal area) and congenital unilateral linear porokeratosis.^8,9

Linear porokeratosis appears in infancy or childhood with plaques that follow the lines of Blaschko.^5,6 Most commonly, it presents unilaterally with annular plaques and linear hyperkeratotic papules that preferentially affect the extremities, though it also may present in a more generalized form or appear in a zosteriform pattern.^10,11 Linear porokeratosis affects fewer than 20,000 individuals in the United States and accounts for fewer than 13% of all porokeratosis cases.^12,13

Despite its relatively low prevalence, early identification of linear porokeratosis is important due to its high oncogenic potential, with malignant transformation to basal cell carcinoma or, more commonly, SCC reported in 19% of reported cases.^1,5,7,14 The malignant transformation rate of linear porokeratosis is reported to be higher than rates seen in other porokeratosis subtypes (9.5%, 7.6%, and 3.4% for PPPD, porokeratosis of Mibelli, and DSAP, respectively).⁷ The risk of malignant transformation from porokeratosis increases with exposure to ionizing radiation, duration of the lesion, larger or coalescing lesions, and advanced age.^7,15,16 Histologic studies have provided support for correlation between lesion size and oncogenic potential, with greater numbers of mitotic cells and more abnormal DNA ploidy seen in larger lesions.¹⁷

Histopathology
All subtypes of porokeratosis share certain histopathologic features that aid in the diagnosis of the disorder.¹⁸ Identification of the clinically observed hyperkeratotic ridged border or cornoid lamella is the primary means of definitively diagnosing porokeratosis; however, cornoid lamellae may be observed in other conditions, including verruca vulgaris and actinic keratosis.^4,14

The cornoid lamella appears as a skewed column of densely packed parakeratotic cells with pyknotic basophilic nuclei extending through the stratum corneum from an epidermal invagination.⁴ Directly beneath the cornoid lamella, the granular layer is markedly diminished or absent, and cells of the stratum spinosum may demonstrate vacuolar changes or dyskeratosis.^4,19 The superficial layer of the cornoid lamella may appear to be more centrifugally located and the cornoid lamella may be seen in several locations throughout the lesion.^2,20 The degree of epidermal invagination, which is present under the cornoid lamella, varies by porokeratosis subtype; the central portion of the lesion may contain epidermis that ranges from hyperplastic to atrophic.² Shumack et al²¹ noted that histologic changes under the cornoid lamella may include a lichenoid tissue reaction, papillary dermal lymphocytic infiltrate, vacuolar changes, dyskeratosis, and liquefaction degeneration of the basal layer. Because many of these histologic features also can be identified in lichen planus, a biopsy of the edge of lesions of porokeratosis is essential for making the correct diagnosis.

Heritability
Although linear porokeratosis has no identified pattern of inheritance and appears sporadic in onset, reports have described concomitant occurrence of linear porokeratosis and DSAP as well as linear porokeratosis arising in children of parents who have a diagnosis of DSAP.^5,18,22,23 Based on these findings, it has been hypothesized that linear porokeratosis may represent a mosaic or segmental form of autosomal-dominant inherited subtypes of porokeratosis, such as DSAP.⁵ According to this hypothesis, loss of heterozygosity in patients with a DSAP mutation during early embryogenesis leads to proliferation of cells that are homozygous or hemizygous for the underlying mutation along lines of Blaschko.²⁴ It has been suggested that the allelic loss implicated in the development of linear porokeratosis is the first step in a multistage process of carcinogenesis, which may help to explain the higher rates of malignant transformation that can be seen in linear porokeratosis.²⁴

Management
Several treatment options exist for porokeratosis, including cryotherapy, topical 5-fluorouracil with or without adjunctive retinoid treatment, topical imiquimod, CO₂ laser, shave and linear excision, curettage, dermabrasion, and oral acitretin for widespread lesions.^1,25-29 One case report detailed successful treatment of adult-onset linear porokeratosis with tacrolimus ointment 0.1%.³⁰ Treatments for porokeratosis demonstrate variable degrees of success, with the aim of eradicating the clonal population of mutant keratinocytes.² Additionally, protection from UV radiation should be encouraged, especially in patients who have lesions that occur in areas of high actinic damage.¹

Conclusion

We report of a case of linear porokeratosis with associated multiple SCCs that developed within the lesion. Definitive diagnosis of linear porokeratosis is important due to the higher rate of malignant transformation than the rate seen in other porokeratoses. In larger lesions, appropriate sampling and orientation of the pathology specimen is essential for identifying cornoid lamellae, thus allowing for appropriate follow-up and management. Several treatment options are available, though evidence for the effectiveness of any particular therapy is lacking. Research has shed light on possible genetic and molecular abnormalities in linear porokeratosis, but the exact pathogenesis of the disorder remains unclear.

Lesions of porokeratosis are thought to arise from disordered keratinization, though the exact pathogenesis remains uncertain. At least 5 clinical subtypes of porokeratosis have been identified: porokeratosis of Mibelli, disseminated superficial porokeratosis and disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, punctuate porokeratosis, and porokeratosis palmaris et plantaris disseminata (PPPD).^1,2 Linear porokeratosis is a rare subtype with a clinical differential diagnosis that includes lichen striatus, linear lichen planus, linear verrucous epidermal nevus, segmental Darier disease, and incontinentia pigmenti.³ Definitive diagnosis of linear porokeratosis is made by histopathologic examination demonstrating a cornoid lamella, defined as a column of parakeratotic cells that lies at 45°to the surface of the epidermis and contains pyknotic basophilic nuclei.⁴ Patients with linear porokeratosis typically develop lesions along the lines of Blaschko in infancy or childhood.^5,6 Among the different subtypes of porokeratosis, linear porokeratosis demonstrates the highest rate of malignant transformation, therefore requiring close clinical observation.⁷

Case Report

An 83-year-old woman presented to the outpatient clinic with a large linear plaque on the right leg that had been present since birth. Ten years prior to presentation, a portion of the lesion started to bleed; biopsy of the area was performed by an outside provider demonstrating squamous cell carcinoma (SCC), which was treated with wide local excision. One year prior to presentation, a separate portion of the plaque was biopsied by an outside provider and another diagnosis of SCC was made.

On examination performed during the initial presentation to our clinic, there was a well-demarcated tan to violaceous linear plaque present at the lower buttock and extending along the posterior leg to the skin overlying the Achilles tendon and dorsal aspect of the right foot. Within the plaque, there were areas of atrophy and areas of inflammation, induration, and hyperkeratosis (Figures 1 and 2). Two punch biopsies were performed: one from the edge of the plaque and one from a hyperkeratotic region within the plaque. Histology from the edge of the plaque demonstrated a cornoid lamella, consistent with a porokeratosis (Figure 3), whereas the histology from the hyperkeratotic region demonstrated a lichenoid infiltrate (Figure 4).

Several treatment options directed at the entire lesion were offered to the patient, but she declined these therapies and opted to address only those areas with clinical features of SCC, such as hyperkeratosis, bleeding, and rapid growth. Although biopsies performed by an outside provider were consistent with SCC, it had not been detected on biopsy performed during her initial visit to our clinic.

The patient was educated on the risk associated with her condition and instructed to follow up every 6 months to monitor for the development of SCC.

Comment

Porokeratosis is a disorder of keratinization with at least 5 clinical subtypes that share histologic similarities: porokeratosis of Mibelli, disseminated superficial porokeratosis and DSAP, linear porokeratosis, punctate porokeratosis, and PPPD.^1,2 Other less common variants of porokeratosis include porokeratosis ptychotropica (a verrucous variant confined to the perianal area) and congenital unilateral linear porokeratosis.^8,9

Linear porokeratosis appears in infancy or childhood with plaques that follow the lines of Blaschko.^5,6 Most commonly, it presents unilaterally with annular plaques and linear hyperkeratotic papules that preferentially affect the extremities, though it also may present in a more generalized form or appear in a zosteriform pattern.^10,11 Linear porokeratosis affects fewer than 20,000 individuals in the United States and accounts for fewer than 13% of all porokeratosis cases.^12,13

Despite its relatively low prevalence, early identification of linear porokeratosis is important due to its high oncogenic potential, with malignant transformation to basal cell carcinoma or, more commonly, SCC reported in 19% of reported cases.^1,5,7,14 The malignant transformation rate of linear porokeratosis is reported to be higher than rates seen in other porokeratosis subtypes (9.5%, 7.6%, and 3.4% for PPPD, porokeratosis of Mibelli, and DSAP, respectively).⁷ The risk of malignant transformation from porokeratosis increases with exposure to ionizing radiation, duration of the lesion, larger or coalescing lesions, and advanced age.^7,15,16 Histologic studies have provided support for correlation between lesion size and oncogenic potential, with greater numbers of mitotic cells and more abnormal DNA ploidy seen in larger lesions.¹⁷

Histopathology
All subtypes of porokeratosis share certain histopathologic features that aid in the diagnosis of the disorder.¹⁸ Identification of the clinically observed hyperkeratotic ridged border or cornoid lamella is the primary means of definitively diagnosing porokeratosis; however, cornoid lamellae may be observed in other conditions, including verruca vulgaris and actinic keratosis.^4,14

The cornoid lamella appears as a skewed column of densely packed parakeratotic cells with pyknotic basophilic nuclei extending through the stratum corneum from an epidermal invagination.⁴ Directly beneath the cornoid lamella, the granular layer is markedly diminished or absent, and cells of the stratum spinosum may demonstrate vacuolar changes or dyskeratosis.^4,19 The superficial layer of the cornoid lamella may appear to be more centrifugally located and the cornoid lamella may be seen in several locations throughout the lesion.^2,20 The degree of epidermal invagination, which is present under the cornoid lamella, varies by porokeratosis subtype; the central portion of the lesion may contain epidermis that ranges from hyperplastic to atrophic.² Shumack et al²¹ noted that histologic changes under the cornoid lamella may include a lichenoid tissue reaction, papillary dermal lymphocytic infiltrate, vacuolar changes, dyskeratosis, and liquefaction degeneration of the basal layer. Because many of these histologic features also can be identified in lichen planus, a biopsy of the edge of lesions of porokeratosis is essential for making the correct diagnosis.

Heritability
Although linear porokeratosis has no identified pattern of inheritance and appears sporadic in onset, reports have described concomitant occurrence of linear porokeratosis and DSAP as well as linear porokeratosis arising in children of parents who have a diagnosis of DSAP.^5,18,22,23 Based on these findings, it has been hypothesized that linear porokeratosis may represent a mosaic or segmental form of autosomal-dominant inherited subtypes of porokeratosis, such as DSAP.⁵ According to this hypothesis, loss of heterozygosity in patients with a DSAP mutation during early embryogenesis leads to proliferation of cells that are homozygous or hemizygous for the underlying mutation along lines of Blaschko.²⁴ It has been suggested that the allelic loss implicated in the development of linear porokeratosis is the first step in a multistage process of carcinogenesis, which may help to explain the higher rates of malignant transformation that can be seen in linear porokeratosis.²⁴

Management
Several treatment options exist for porokeratosis, including cryotherapy, topical 5-fluorouracil with or without adjunctive retinoid treatment, topical imiquimod, CO₂ laser, shave and linear excision, curettage, dermabrasion, and oral acitretin for widespread lesions.^1,25-29 One case report detailed successful treatment of adult-onset linear porokeratosis with tacrolimus ointment 0.1%.³⁰ Treatments for porokeratosis demonstrate variable degrees of success, with the aim of eradicating the clonal population of mutant keratinocytes.² Additionally, protection from UV radiation should be encouraged, especially in patients who have lesions that occur in areas of high actinic damage.¹

Conclusion

We report of a case of linear porokeratosis with associated multiple SCCs that developed within the lesion. Definitive diagnosis of linear porokeratosis is important due to the higher rate of malignant transformation than the rate seen in other porokeratoses. In larger lesions, appropriate sampling and orientation of the pathology specimen is essential for identifying cornoid lamellae, thus allowing for appropriate follow-up and management. Several treatment options are available, though evidence for the effectiveness of any particular therapy is lacking. Research has shed light on possible genetic and molecular abnormalities in linear porokeratosis, but the exact pathogenesis of the disorder remains unclear.

Lesions of porokeratosis are thought to arise from disordered keratinization, though the exact pathogenesis remains uncertain. At least 5 clinical subtypes of porokeratosis have been identified: porokeratosis of Mibelli, disseminated superficial porokeratosis and disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, punctuate porokeratosis, and porokeratosis palmaris et plantaris disseminata (PPPD).^1,2 Linear porokeratosis is a rare subtype with a clinical differential diagnosis that includes lichen striatus, linear lichen planus, linear verrucous epidermal nevus, segmental Darier disease, and incontinentia pigmenti.³ Definitive diagnosis of linear porokeratosis is made by histopathologic examination demonstrating a cornoid lamella, defined as a column of parakeratotic cells that lies at 45°to the surface of the epidermis and contains pyknotic basophilic nuclei.⁴ Patients with linear porokeratosis typically develop lesions along the lines of Blaschko in infancy or childhood.^5,6 Among the different subtypes of porokeratosis, linear porokeratosis demonstrates the highest rate of malignant transformation, therefore requiring close clinical observation.⁷

Case Report

An 83-year-old woman presented to the outpatient clinic with a large linear plaque on the right leg that had been present since birth. Ten years prior to presentation, a portion of the lesion started to bleed; biopsy of the area was performed by an outside provider demonstrating squamous cell carcinoma (SCC), which was treated with wide local excision. One year prior to presentation, a separate portion of the plaque was biopsied by an outside provider and another diagnosis of SCC was made.

On examination performed during the initial presentation to our clinic, there was a well-demarcated tan to violaceous linear plaque present at the lower buttock and extending along the posterior leg to the skin overlying the Achilles tendon and dorsal aspect of the right foot. Within the plaque, there were areas of atrophy and areas of inflammation, induration, and hyperkeratosis (Figures 1 and 2). Two punch biopsies were performed: one from the edge of the plaque and one from a hyperkeratotic region within the plaque. Histology from the edge of the plaque demonstrated a cornoid lamella, consistent with a porokeratosis (Figure 3), whereas the histology from the hyperkeratotic region demonstrated a lichenoid infiltrate (Figure 4).

Several treatment options directed at the entire lesion were offered to the patient, but she declined these therapies and opted to address only those areas with clinical features of SCC, such as hyperkeratosis, bleeding, and rapid growth. Although biopsies performed by an outside provider were consistent with SCC, it had not been detected on biopsy performed during her initial visit to our clinic.

The patient was educated on the risk associated with her condition and instructed to follow up every 6 months to monitor for the development of SCC.

Comment

Porokeratosis is a disorder of keratinization with at least 5 clinical subtypes that share histologic similarities: porokeratosis of Mibelli, disseminated superficial porokeratosis and DSAP, linear porokeratosis, punctate porokeratosis, and PPPD.^1,2 Other less common variants of porokeratosis include porokeratosis ptychotropica (a verrucous variant confined to the perianal area) and congenital unilateral linear porokeratosis.^8,9

Linear porokeratosis appears in infancy or childhood with plaques that follow the lines of Blaschko.^5,6 Most commonly, it presents unilaterally with annular plaques and linear hyperkeratotic papules that preferentially affect the extremities, though it also may present in a more generalized form or appear in a zosteriform pattern.^10,11 Linear porokeratosis affects fewer than 20,000 individuals in the United States and accounts for fewer than 13% of all porokeratosis cases.^12,13

Despite its relatively low prevalence, early identification of linear porokeratosis is important due to its high oncogenic potential, with malignant transformation to basal cell carcinoma or, more commonly, SCC reported in 19% of reported cases.^1,5,7,14 The malignant transformation rate of linear porokeratosis is reported to be higher than rates seen in other porokeratosis subtypes (9.5%, 7.6%, and 3.4% for PPPD, porokeratosis of Mibelli, and DSAP, respectively).⁷ The risk of malignant transformation from porokeratosis increases with exposure to ionizing radiation, duration of the lesion, larger or coalescing lesions, and advanced age.^7,15,16 Histologic studies have provided support for correlation between lesion size and oncogenic potential, with greater numbers of mitotic cells and more abnormal DNA ploidy seen in larger lesions.¹⁷

Histopathology
All subtypes of porokeratosis share certain histopathologic features that aid in the diagnosis of the disorder.¹⁸ Identification of the clinically observed hyperkeratotic ridged border or cornoid lamella is the primary means of definitively diagnosing porokeratosis; however, cornoid lamellae may be observed in other conditions, including verruca vulgaris and actinic keratosis.^4,14

The cornoid lamella appears as a skewed column of densely packed parakeratotic cells with pyknotic basophilic nuclei extending through the stratum corneum from an epidermal invagination.⁴ Directly beneath the cornoid lamella, the granular layer is markedly diminished or absent, and cells of the stratum spinosum may demonstrate vacuolar changes or dyskeratosis.^4,19 The superficial layer of the cornoid lamella may appear to be more centrifugally located and the cornoid lamella may be seen in several locations throughout the lesion.^2,20 The degree of epidermal invagination, which is present under the cornoid lamella, varies by porokeratosis subtype; the central portion of the lesion may contain epidermis that ranges from hyperplastic to atrophic.² Shumack et al²¹ noted that histologic changes under the cornoid lamella may include a lichenoid tissue reaction, papillary dermal lymphocytic infiltrate, vacuolar changes, dyskeratosis, and liquefaction degeneration of the basal layer. Because many of these histologic features also can be identified in lichen planus, a biopsy of the edge of lesions of porokeratosis is essential for making the correct diagnosis.

Heritability
Although linear porokeratosis has no identified pattern of inheritance and appears sporadic in onset, reports have described concomitant occurrence of linear porokeratosis and DSAP as well as linear porokeratosis arising in children of parents who have a diagnosis of DSAP.^5,18,22,23 Based on these findings, it has been hypothesized that linear porokeratosis may represent a mosaic or segmental form of autosomal-dominant inherited subtypes of porokeratosis, such as DSAP.⁵ According to this hypothesis, loss of heterozygosity in patients with a DSAP mutation during early embryogenesis leads to proliferation of cells that are homozygous or hemizygous for the underlying mutation along lines of Blaschko.²⁴ It has been suggested that the allelic loss implicated in the development of linear porokeratosis is the first step in a multistage process of carcinogenesis, which may help to explain the higher rates of malignant transformation that can be seen in linear porokeratosis.²⁴

Management
Several treatment options exist for porokeratosis, including cryotherapy, topical 5-fluorouracil with or without adjunctive retinoid treatment, topical imiquimod, CO₂ laser, shave and linear excision, curettage, dermabrasion, and oral acitretin for widespread lesions.^1,25-29 One case report detailed successful treatment of adult-onset linear porokeratosis with tacrolimus ointment 0.1%.³⁰ Treatments for porokeratosis demonstrate variable degrees of success, with the aim of eradicating the clonal population of mutant keratinocytes.² Additionally, protection from UV radiation should be encouraged, especially in patients who have lesions that occur in areas of high actinic damage.¹

Conclusion

We report of a case of linear porokeratosis with associated multiple SCCs that developed within the lesion. Definitive diagnosis of linear porokeratosis is important due to the higher rate of malignant transformation than the rate seen in other porokeratoses. In larger lesions, appropriate sampling and orientation of the pathology specimen is essential for identifying cornoid lamellae, thus allowing for appropriate follow-up and management. Several treatment options are available, though evidence for the effectiveness of any particular therapy is lacking. Research has shed light on possible genetic and molecular abnormalities in linear porokeratosis, but the exact pathogenesis of the disorder remains unclear.

FROM JAAD

Squamous cell carcinomas (SCC), but not basal cell carcinomas (BCC), were associated with a risk of death from any cause that was 25% higher than that seen in the general population, based on a systematic literature review and meta-analysis published in the Journal of American Academy of Dermatology (2017. doi: 10.1016/j.jaad.2017.11.026).

“Because these tumors often occur in the same patients and are both often caused by exposure to ultraviolet radiation, patients with BCC and SCC are often grouped together,” Mackenzie R. Wehner, MD, of the University of Pennsylvania, Philadelphia, and co-authors wrote. “Our data contributes to the argument that the carcinogenesis of these tumors and long-term outcomes for patients with these tumors may be distinct.”

Patients with SCC “may need additional education and age-appropriate screening to prevent deaths from major diseases,” the authors concluded.
Dr. Wehner and colleagues systematically searched the medical literature and found four studies encompassing a total of 175,849 patients with SCC and 464,230 patients with BCC.

Kelly Nelson/National Cancer Institute/Wikimedia Commons

Relative to the general population, mortality for those with an SCC was 1.25 (95% CI, 1.17-1.32). At 0.92 (95% CI 0.83-1.02), there was no significant difference in mortality for patients with a BCC.

Collectively and individually, the studies found a statistically significant increased relative mortality for having SCC.
There are clear distinctions between BCC and SCC with regard to histology, pathophysiology, survival, and other parameters, the study authors said. “While many patients get both BCC and SCC, future research should take into account that these cancers may have different long-term risks and outcomes.”

FROM JAAD

Squamous cell carcinomas (SCC), but not basal cell carcinomas (BCC), were associated with a risk of death from any cause that was 25% higher than that seen in the general population, based on a systematic literature review and meta-analysis published in the Journal of American Academy of Dermatology (2017. doi: 10.1016/j.jaad.2017.11.026).

“Because these tumors often occur in the same patients and are both often caused by exposure to ultraviolet radiation, patients with BCC and SCC are often grouped together,” Mackenzie R. Wehner, MD, of the University of Pennsylvania, Philadelphia, and co-authors wrote. “Our data contributes to the argument that the carcinogenesis of these tumors and long-term outcomes for patients with these tumors may be distinct.”

Patients with SCC “may need additional education and age-appropriate screening to prevent deaths from major diseases,” the authors concluded.
Dr. Wehner and colleagues systematically searched the medical literature and found four studies encompassing a total of 175,849 patients with SCC and 464,230 patients with BCC.

Kelly Nelson/National Cancer Institute/Wikimedia Commons

Relative to the general population, mortality for those with an SCC was 1.25 (95% CI, 1.17-1.32). At 0.92 (95% CI 0.83-1.02), there was no significant difference in mortality for patients with a BCC.

Collectively and individually, the studies found a statistically significant increased relative mortality for having SCC.
There are clear distinctions between BCC and SCC with regard to histology, pathophysiology, survival, and other parameters, the study authors said. “While many patients get both BCC and SCC, future research should take into account that these cancers may have different long-term risks and outcomes.”

FROM JAAD

Squamous cell carcinomas (SCC), but not basal cell carcinomas (BCC), were associated with a risk of death from any cause that was 25% higher than that seen in the general population, based on a systematic literature review and meta-analysis published in the Journal of American Academy of Dermatology (2017. doi: 10.1016/j.jaad.2017.11.026).

“Because these tumors often occur in the same patients and are both often caused by exposure to ultraviolet radiation, patients with BCC and SCC are often grouped together,” Mackenzie R. Wehner, MD, of the University of Pennsylvania, Philadelphia, and co-authors wrote. “Our data contributes to the argument that the carcinogenesis of these tumors and long-term outcomes for patients with these tumors may be distinct.”

Patients with SCC “may need additional education and age-appropriate screening to prevent deaths from major diseases,” the authors concluded.
Dr. Wehner and colleagues systematically searched the medical literature and found four studies encompassing a total of 175,849 patients with SCC and 464,230 patients with BCC.

Kelly Nelson/National Cancer Institute/Wikimedia Commons

Relative to the general population, mortality for those with an SCC was 1.25 (95% CI, 1.17-1.32). At 0.92 (95% CI 0.83-1.02), there was no significant difference in mortality for patients with a BCC.

Collectively and individually, the studies found a statistically significant increased relative mortality for having SCC.
There are clear distinctions between BCC and SCC with regard to histology, pathophysiology, survival, and other parameters, the study authors said. “While many patients get both BCC and SCC, future research should take into account that these cancers may have different long-term risks and outcomes.”