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Psoriasis is an inflammatory disease with systemic manifestations that most commonly presents as itchy, erythematous, scaly plaques on extensor surfaces. Activation of the IL-23/IL-17 pro-inflammatory signaling pathway is a hallmark of psoriasis and its inhibition is key to clinical management. Granzyme K (GzmK) is an immune cell-secreted serine protease elevated in inflammatory and proliferative skin conditions. In the present study, human psoriasis lesions exhibited elevated GzmK levels compared to non-lesional psoriasis and healthy control skin. In an established murine model of imiquimod (IMQ)-induced psoriasis, genetic loss of GzmK significantly reduced disease severity, as determined by delayed plaque formation, decreased erythema and desquamation, reduced epidermal thickness, and inflammatory infiltrate. Molecular characterization in vitro revealed that GzmK contributed to macrophage secretion of IL-23 as well as PAR-1-dependent keratinocyte proliferation. These findings demonstrate that GzmK enhances IL-23-driven inflammation as well as keratinocyte proliferation to exacerbate psoriasis severity.

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BACKGROUND: Psoralen + ultraviolet-A (PUVA) is associated with photocarcinogenesis. However, carcinogenic risk with other ultraviolet phototherapies remains unclear. OBJECTIVE: Evaluate whether phototherapy without psoralens increases skin cancer risk. METHODS: Retrospective cohort study of patients treated at a teaching-hospital phototherapy center (1977-2018). Skin cancer records were validated against pathology reports. Age-standardized incidence rates (ASIRs) of skin cancer were evaluated for gender, skin phototype, diagnosis, ultraviolet modality, anatomical site; and compared to provincial population incidence rates (2003). RESULTS: In total, 3506 patients treated with broadband-ultraviolet-B, narrowband-UVB and/or combined UVAB were assessed with a mean follow-up of 7.3 years. Majority of patients had psoriasis (60.9%) or eczema (26.4%). Median number of treatments was 43 (1-3598). Overall, 170 skin cancers (17 melanoma, 33 squamous cell carcinoma and 120 basal cell carcinoma) occurred in 79 patients. Patient-based and tumor-based ASIR of skin cancer was 149 (95% CI: 112-187)/100,000 and 264 (219-309)/100,000 person-years, respectively. There was no significant difference between tumor-based ASIRs for melanoma, squamous cell carcinoma, and basal cell carcinoma compared to the general population; or in phototherapy patients with-psoriasis or eczema; or immunosuppressants. No cumulative dose-response correlation between UVB and skin cancer was seen. LIMITATIONS: Treatment and follow-up duration. CONCLUSION: No increased risk of melanoma and keratinocyte cancer was found with phototherapy.

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Vulvovaginal melanoma (VVM) is a rare but deadly disease, accounting for 5% of all vulvar malignancies, with a 5-yr survival rate of only 47% for all stages of the disease. VVM is a distinct subset of melanoma, with a unique genomic profile and underlying pathogenesis unassociated with sun exposure. Distinguishing these rare malignancies from very common pigmented lesions of the vulva and vagina is challenging as histologic features often overlap between entities. PReferentially expressed Antigen in MElanoma (PRAME) is a melanoma-associated protein, and immunohistochemistry (IHC) for PRAME distinguishes cutaneous, oral mucosal, and retinal melanoma from atypical nevi. Given the biological differences between VVM and cutaneous melanoma, the utility of PRAME IHC for the diagnosis of VVM is unknown. We accrued a cohort of 20 VVM and 21 benign vulvar melanocytic nevi. We found that nuclear PRAME IHC staining with 4+ intensity was present in 85% of the VVM and 0% of the nevi. With the assistance of PRAME IHC, we found evidence of close or positive margin involvement in 3 of 10 cases where margins were originally diagnosed as negative for melanoma in situ. Our study is the first to assess PRAME IHC in a cohort of VVM cases and provides confidence for using PRAME IHC to assist with diagnosis and margin assessment in this rare disease.

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ABSTRACT: The human progenitor-cell antigen CD34 is expressed in dermal dendritic cells and is lost in several disorders affecting dermal collagen. The loss of CD34 immunohistochemical staining has been demonstrated to be helpful in the histologic diagnosis of morphea, lichen sclerosus, and the classic pattern of granuloma annulare. This study characterized CD34 expression in 2 sclerosing disorders affecting the subcutis: lipodermatosclerosis (LDS) and the sclerodermoid form of chronic graft-versus-host disease (ScGVHD). In addition, we applied CD34 staining to the interstitial pattern of granuloma annulare (IGA), which is a diagnostically challenging entity with subtle amounts of dermal collagen degeneration. Fifteen cases of LDS, 6 cases of ScGVHD, and 4 cases of IGA were identified and stained with CD34. All cases of LDS showed loss of CD34 within subcutaneous septa, and 9 cases (60%) also exhibited full-thickness dermal loss of interstitial staining. All 6 cases of ScGVHD showed varying degrees of CD34 loss within the dermis and/or subcutaneous septa. The normal subcutis showed diffuse septal staining with CD34, with a density equal to that seen in the dermis. CD34 staining was lost in areas of dermal inflammation in half of the IGA cases. We conclude that CD34 staining is a useful ancillary test in disease processes affecting the subcutaneous collagen such as LDS and ScGVHD. Its utility also extends to diagnostically challenging disorders of dermal collagen degeneration such as IGA.

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TNFα-inhibitor-induced psoriasis is mediated by the type-I interferon pathway, of which IFNα, LL37 and IL-36γ are major players. A subset of patients treated with TNFα inhibitors develop small plaque psoriatic lesions. Small plaque psoriasis is similarly observed in patients on immune checkpoint inhibitors (ICI), and with concurrent systemic lupus erythematosus (SLE) or positive antinuclear antibody (ANA). Small plaque psoriasis is also the predominant phenotype in Asian populations. The association between small plaque psoriasis morphology in various clinical scenarios and the type-I interferon pathway has not been previously studied. A cross-sectional study was conducted of patients who developed small plaque psoriasis and had a biopsy for diagnostic clarification between 2009 and 2017. We obtained skin specimens from 14 adults with small plaque psoriasis: four patients taking anti-TNFα treatment, four patients with antecedent SLE, three patients with concurrent ANA positivity and three patients taking ICI. Controls included three patients with chronic plaque psoriasis. Histology confirmed psoriasiform epidermal hyperplasia with focal lichenoid and spongiotic features. Immunohistochemical analysis revealed higher expression of IFNα-induced MXA, LL37 and IL-36γ in all clinical scenarios of small plaque psoriasis compared to chronic plaque psoriasis. There was decreased CD8 T-cell migration to the epidermis and variability in the number of LAMP3+ cytoplasmic dendritic cells in the dermis of small plaque psoriasis. The findings suggest that small plaque psoriasis is a unique type of psoriasis with a distinct morphology and immune-phenotype, primarily mediated by the type-I interferon pathway. Associating morphology and disease pathogenesis may help identify therapeutic targets for better disease control.

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Pemphigoid diseases refer to a group of severe autoimmune skin blistering diseases characterized by subepidermal blistering and loss of dermal-epidermal adhesion induced by autoantibody and immune cell infiltrate at the dermal-epidermal junction and upper dermis. Here, we explore the role of the immune cell-secreted serine protease, granzyme B, in pemphigoid disease pathogenesis using three independent murine models. In all models, granzyme B knockout or topical pharmacological inhibition significantly reduces total blistering area compared to controls. In vivo and in vitro studies show that granzyme B contributes to blistering by degrading key anchoring proteins in the dermal-epidermal junction that are necessary for dermal-epidermal adhesion. Further, granzyme B mediates IL-8/macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity. Clinically, granzyme B is elevated and abundant in human pemphigoid disease blister fluids and lesional skin. Collectively, granzyme B is a potential therapeutic target in pemphigoid diseases.

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AIMS: Differentiated vulvar intraepithelial neoplasia (dVIN), the precursor lesion to human papillomavirus-independent vulvar squamous cell carcinoma (VSCC), can be difficult to distinguish from vulvar inflammatory dermatoses. Our goal was to determine if p53 could be a useful biomarker for dVIN, by characterizing p53 percentage, intensity and patterns of staining in dVIN and its histological mimics. METHODS AND RESULTS: We studied p53 immunohistochemical staining patterns in 16 dVIN cases and 46 vulvar non-neoplastic squamous lesions [12 lichen sclerosus (LS); seven lichen simplex chronicus; three lichen planus (LP); six psoriasis; 13 spongiotic dermatitis (SPO); and five candidiasis]. dVIN cases were adjacent to a p16-negative invasive VSCC in resection specimens. All dVIN cases showed null-type or moderate to strong uniform p53 staining in >70% of basal cells, with moderate to strong continuous parabasal staining extending to two-thirds of the epidermis. This was in contrast to weak or weak to moderate patchy p53 staining in the majority of other lesions. Moderate to strong and increased basal p53 staining (≥70%) was also observed in a subset of LS cases (5/12, 42%), LP cases (1/3, 33%), and SPO cases (36%, 4/11); however, in all categories, this was limited to the basal layer, and any staining in the parabasal layers was patchy. CONCLUSION: Strong and uniform p53 staining of basal cells, extending into the parabasal layers, and a complete absence of staining (null type) is useful in distinguishing dVIN from other mimics in the vulva. p53 staining of lesser intensity or quantity, particularly basal overexpression only, overlaps with that in vulvar inflammatory lesions.

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AL amyloidosis is a complication of B-cell dyscrasias and multiple myeloma, manifest as deposition of antibody fragments in many different organs, including the skin. We describe a rare case of this systemic disease which presented with isolated scalp alopecia. Further investigation led to the diagnosis of an occult plasma-cell dyscrasia, showing the benefit of including systemic amyloidosis in the differential diagnosis of alopecia. The biopsy finding of cutaneous amyloidosis should prompt further workup to exclude an underlying pathology.

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BACKGROUND: Ki-67 is an immunohistochemical stain used as a nuclear proliferation marker. It is nonspecific, and is expressed in all active phases of the cell cycle. Vulvar vestibular papules in women and pearly penile papules in men are benign fibrous papules on the genitals, are noninfectious, and do not require treatment. However, these lesions can be clinically confused with condylomata acuminata induced by human papillomavirus (HPV), which have medical and social implications. OBJECTIVE: Because HPV infection is known to induce expression of proliferation markers, we propose that Ki-67 be used to differentiate condylomata acuminata from vulvar vestibular papules or pearly penile papules on pathologic examination. METHODS: We reviewed a total of 26 lesions from 18 patients of previously pathologically diagnosed lesions, including condylomata acuminata (11 lesions), vulvar vestibular papules (10 lesions), and pearly penile papules (5 lesions). All slides were stained with Ki-67, reviewed, and categorized as positive or negative for Ki-67 staining by 1 investigator who was unaware of the original diagnosis. RESULTS: Eleven out of 11 cases of condylomata acuminata were identified as positive for Ki-67 staining. Ten out of 10 cases of vulvar vestibular papules were negative for Ki-67. Five out of 5 cases of pearly penile papules were negative for Ki-67. CONCLUSION: Ki-67 is a reliable marker to pathologically distinguish benign vulvar vestibular papules in women, or pearly penile papules in men, from HPV-induced condylomata acuminata.

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In healthy skin, epidermis and dermis are anchored together at the dermal-epidermal junction (DEJ), a specialized basement membrane pivotal for skin integrity and function. However, increased inflammation in the DEJ is associated with the disruption and separation of this junction and sub-epidermal blistering. Granzyme B (GzmB) is a serine protease secreted by immune cells. Dysregulated inflammation may lead to increased GzmB accumulation and proteolysis in the extracellular milieu. Although elevated GzmB is observed at the level of the DEJ in inflammatory and blistering skin conditions, the present study is the first to explore GzmB in the context of DEJ degradation in autoimmune sub-epidermal blistering. In the present study, GzmB induced separation of the DEJ in healthy human skin. Subsequently, α6/ß4 integrin, collagen VII, and collagen XVII were identified as extracellular substrates for GzmB through western blot, and specific cleavage sites were identified by mass spectrometry. In human bullous pemphigoid, dermatitis herpetiformis, and epidermolysis bullosa acquisita, GzmB was elevated at the DEJ when compared to healthy samples, while α6/ß4 integrin, collagen VII, and collagen XVII were reduced or absent in the area of blistering. In summary, our results suggest that regardless of the initial causation of sub-epidermal blistering, GzmB activity is a common final pathway that could be amenable to a single targeted treatment approach.

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BACKGROUND: Bullous pemphigoid (BP) is the most common subepidermal autoimmune disorder characterized by tense bullae. It is associated with circulating autoantibodies against BP antigen-1 and BP antigen-2. Diagnosis is based upon clinical, histopathologic, and immunopathologic examination. Direct immunofluorescence (DIF) of perilesional skin highlights C3 with or without IgG in a linear pattern along the basement membrane. OBJECTIVES: We hypothesized that repeat biopsies may be required for a definitive DIF diagnosis of BP, as initial DIF evaluation may result in a false-negative result. METHODS: A retrospective chart review was conducted on 1143 specimens collected for evaluation for BP. Cases from 2 Vancouver Coastal Health Authority laboratories from 2006 to 2016 were reviewed. Results were interpreted as positive, negative, or indeterminate based on pathologic description and specimen quality. RESULTS: After meeting the inclusion criteria, 739 specimens were further evaluated. There were 289 cases of BP in the 10-year period. Five patients (1.73%; 95% confidence interval [CI], 1.50-1.96) required a second biopsy to support a BP diagnosis, and within this group, 1.04% of the 289 (95% CI, 0.811-1.27) were true successive negative-to-positive DIF results. CONCLUSIONS: DIF is the most reliable test used to diagnose BP; however, a small percentage of patients will initially have a negative result. False-negative or indeterminate results may be due to specimen sampling from lesional skin or due to a subthreshold quantity of immune complexes in the skin. Repeat biopsy is warranted despite an initial negative DIF if BP is clinically suspected.

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BACKGROUND: It has been postulated that periodic acid-Schiff staining of basement membrane can predict direct immunofluorescence patterns seen in epidermolysis bullosa acquisita and bullous pemphigoid. It has also been suggested that the type of inflammatory infiltrate or presence of fraying of basal keratinocytes may differentiate these two conditions. OBJECTIVE: In this study, we aimed to confirm these observations. METHODS: We reviewed 13 cases of direct immunofluorescence-confirmed epidermolysis bullosa acquisita and 19 cases of direct immunofluorescence-confirmed bullous pemphigoid, all with a subepidermal blister in the routinely processed specimen. The gold standard for diagnosis of epidermolysis bullosa acquisita vs bullous pemphigoid was taken to be identification of immune deposits on the dermal side ('floor' for epidermolysis bullosa acquisita) or the epidermal side ('roof' for bullous pemphigoid) of the salt-split direct immunofluorescence specimen. Our tests to distinguish epidermolysis bullosa acquisita from bullous pemphigoid on the routinely processed biopsy included periodic acid-Schiff basement membrane on the blister roof, neutrophilic infiltrate, lack of eosinophilic infiltrate, and absence of keratinocyte fraying. RESULTS: Sensitivity and specificity for each test were as follows: periodic acid-Schiff staining of roof (sensitivity 25%, specificity 95%), neutrophilic infiltrate (sensitivity 54%, specificity 74%), lack of eosinophilic infiltrate (sensitivity 92%, specificity 68%), and absence of keratinocyte fraying (sensitivity 62%, specificity 58%). CONCLUSIONS: Features in the routinely processed biopsy were unable to reliably distinguish between epidermolysis bullosa acquisita and bullous pemphigoid. Direct immunofluorescence on salt-split skin remains the standard for differentiation.

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BACKGROUND: Cytomegalovirus (CMV) is a highly prevalent herpesvirus that can present with cutaneous disease in immunocompromised individuals. This may reflect systemic involvement, which is associated with significant morbidity and mortality. OBJECTIVE: To report a case of cutaneous CMV in an immunocompromised patient and to discuss the differential diagnosis of genital ulcers. METHODS: A medical chart review was conducted on a patient who presented with a scrotal ulcer after renal transplantation. A review of the literature on cutaneous CMV disease was also completed. RESULTS: Biopsy of the scrotal ulcer revealed classic findings of CMV disease. The patient also developed CMV viremia. Treatment with valganciclovir resolved his scrotal ulcer and viremia. CONCLUSION: The differential diagnosis for genital ulcers is broad, especially in the immunocompromised patient. Cutaneous CMV disease should be ruled out with biopsy and immunohistochemical examination in immunocompromised patients, as it may reflect systemic involvement and significantly affect patient care.

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