Abstract
A 72-year-old female presented with multiple 3-4 mm pearly papules on the upper lip. Shave biopsies were sent with the suspicion of basal cell carcinoma. Two of the biopsies showed portions of a basaloid neoplasm with atypia and focal areas of possible sebaceous differentiation at the base of the tissue biopsy. The differential diagnosis included basal cell carcinoma with focal sebaceous differentiation versus sebaceous carcinoma. Immunohistochemistry was performed. BerEP4 was negative, EMA was focally positive, and PRAME was positive even in purely basaloid foci. Therefore, sebaceous carcinoma was favored. Another biopsy revealed a sebaceous adenoma with loss of MSH2 and MSH6 by immunohistochemistry. The patient is not known to have Muir-Torre syndrome. Sebaceous carcinoma can be difficult to diagnose on initial biopsy if the biopsy is small or sebocytes are not readily evident. Donnell et al. [2021] showed that PRAME is comparable to adipophilin in showing positive staining in sebocytes and basaloid cells of sebaceous neoplasms. Given many laboratories may not have adipophilin in their testing menu, we suggest that PRAME may be a useful substitute to help favor a diagnosis of sebaceous carcinoma over basal cell carcinoma on small biopsies in everyday practice.
Financial Disclosure:
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