PEComa: A Perivascular Epithelioid Cell Tumor in the Liver—A Case Report and Review of the Literature

Perivascular epithelioid cell tumors are soft tissue tumors that can occur in various locations in the body whose incidence is rising. Hepatic PEComas are quite rare and diagnosis involves positivity of Melan-A and HMB45 on immunohistochemistry. Usual treatment is surgery for benign tumors and chemotherapy including mTOR inhibitors for malignant tumors. Here we discuss the radiological and pathological diagnosis, evaluation, and management of a hepatic PEComa. We describe a 51-year-old patient who was diagnosed incidentally after unusual physical exam findings

An Underrecognized Histologic Clue to the Diagnosis of Mucous Membrane Pemphigoid: A Case Report and Review of Diagnostic Guidelines

Mucous membrane pemphigoid (MMP), also known as cicatricial pemphigoid (CP), is a heterogeneous group of subepidermal blistering diseases that affect the mucous membranes, most frequently in the eye and oral cavity. MMP is often unrecognized or misdiagnosed in its early stages due to its rarity and nonspecific presentation. We present the case of a 69-year-old female in which MMP of the vulva was not initially suspected. The first biopsy, from lesional tissue for routine histology, revealed fibrosis, late-stage granulation tissue, and nonspecific findings. A second biopsy, from perilesional tissue for direct immunofluorescence (DIF), revealed DIF findings typical of MMP. Scrutiny of both the first and second biopsies revealed a subtle but telling histologic feature: subepithelial clefts along adnexae in the context of a scarring process with neutrophils and eosinophils, which can be an important clue to MMP. This histologic clue has been previously described; reinforcing its importance may prove useful for future cases, especially those for which DIF is not feasible. Our case demonstrates the protean presentations of MMP, the need for persistence in sampling unusual cases, and the relevance of inconspicuous histologic features. The report highlights this underrecognized yet potentially decisive histologic clue to MMP, reviews current biopsy guidelines when MMP is suspected, and delineates the clinical and morphological features of vulvar MMP

Congenital Atrophic Dermatofibrosarcoma Protuberans: A Case Report and Review of the Literature

Dermatofibrosarcoma protuberans (DFSP) is a rare mesenchymal tumor of intermediate malignant potential. The neoplasm is locally aggressive with a high rate of recurrence. It typically presents in adults. Atrophic congenital DFSP is extremely rare. The few reported cases have presented as a morphea-like plaque that persists for years, before progressing into a nodular form. To our knowledge, congenital atrophic DFSP has been only reported fourteen times, and of those, only nine were confirmed by molecular studies. Herein we report a congenital case of atrophic DFSP, which initially presented as a bruise-like atrophic plaque on the dorsal forearm, initially mistaken for child abuse. The clinical appearance, histopathology, and molecular features of this rare form of DFSP are reviewed. Our case highlights the importance of early detection and adequate sampling of congenital DFSP; early treatment allows for treating small lesions without large, disfiguring, and potentially disabling excisions

Squamoid eccrine ductal carcinoma: clinical, histological and immunohistochemical features

Squamoid eccrine ductal carcinoma (SEDC) is a cutaneous adnexal malignancy that is histologically challenging to distinguish from squamous cell carcinoma. We report three cases of this rare entity and review the present literature regarding clinical, histological, and immunohistochemical features. Patients presented with a single nodule or plaque lesion on their back and temple. The shave biopsies for Patient A and C were interpreted as SEDC. Patient B's initial shave biopsy was interpreted as probable surface of squamous cell carcinoma, and subsequent excision revealed SEDC. Ductal differentiation was confirmed by positive expression of epithelial membrane antigen and carcinoembryonic antigen immunostains in all three patients. Review of the 67 previously reported cases emphasizes the importance of diagnosing SEDC accurately and promptly given its potential for distant metastasis and mortality. Perineural or lymphatic invasion is associated with higher rate of recurrence or metastasis. There should be high pathologic suspicion for SEDC in an elderly patient presenting with a palpable lesion, even if located outside of the head and neck area, particularly when there is suggestion of ductal differentiation in a sample of a squamous neoplasm

A Novel Method to Detect Copy Number Variation in Melanoma: Droplet Digital PCR for Quantitation of the CDKN2A Gene, a Proof-of-Concept Study.

A definitive diagnosis of nevus or melanoma is not always possible for histologically ambiguous melanocytic neoplasms. In such cases, ancillary molecular testing can support a diagnosis of melanoma if certain chromosomal aberrations are detected. Current technologies for copy number variation (CNV) detection include chromosomal microarray analysis (CMA) and fluorescence in situ hybridization. Although CMA and fluorescence in situ hybridization are effective, their utilization can be limited by cost, turnaround time, and inaccessibility outside of large reference laboratories. Droplet digital polymerase chain reaction (ddPCR) is a rapid, automated, and relatively inexpensive technology for CNV detection. We investigated the ability of ddPCR to quantify CNV in cyclin-dependent kinase inhibitor 2A ( CDKN2A ), the most commonly deleted tumor suppressor gene in melanoma. CMA data were used as the gold standard. We analyzed 57 skin samples from 52 patients diagnosed with benign nevi, borderline lesions, primary melanomas, and metastatic melanomas. In a training cohort comprising 29 randomly selected samples, receiver operator characteristic curve analysis revealed an optimal ddPCR cutoff value of 1.73 for calling CDKN2A loss. In a validation cohort comprising the remaining 28 samples, ddPCR detected CDKN2A loss with a sensitivity and specificity of 94% and 90%, respectively. Significantly, ddPCR could also identify whether CDKN2A losses were monoallelic or biallelic. These pilot data suggest that ddPCR can detect CDKN2A deletions in melanocytic tumors with accuracy comparable with CMA. With further validation, ddPCR could provide an additional CNV assay to aid in the diagnosis of challenging melanocytic neoplasms