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Case Reports

Abstract

We describe a case of a basal cell carcinoma with myoepithelial differentiation (BCC with MED). A 72-year-old male presented for a longstanding 1.7cm non-healing skin lesion on his right frontal scalp. Histopathology of the lesion demonstrated two components: one component resembled a typical basal cell carcinoma, and the other demonstrated signet ring cytology. Immunohistochemical expression showed strong staining for BerEp4, confirming a basal cell carcinoma diagnosis. Strong and diffusely positive staining of calponin, smooth muscle actin, and CKAE1/AE3 were noted in the sections with signet ring cytology. The findings together confirmed the diagnosis of basal cell carcinoma with myoepithelial differentiation (BCC with MED). To date, our case represents the eighteenth reported case of BCC with MED. Of available cases, the age range at presentation is 43 to 83 years, with median age approximately 67 years. Men seem to be impacted more than women, with 13 male cases and 5 female cases reported. The largest reported plaque of this tumor measured 10 cm x 6 cm. All identified cases involved the face or scalp. The differential diagnosis of BCC with MED includes, but is not limited to, a desmoplastic component to a BCC, myoepithelioma, myoepithelial carcinoma, sarcomatous component of a biphasic neoplasm, mixed cutaneous benign eccrine or apocrine tumors, and tumors with a prominent signet ring component (such as plasmacytoid squamous cell carcinoma, metastatic carcinomas, etc.). Complete tumor removal using Mohs micrographic surgery is recommended. This case is presented to highlight the distinctive uncommon variant of a common neoplasm.