A Case of Perianal Basal Cell Carcinoma Differentially Diagnosed from Basaloid Carcinoma Using Immunohistochemistry for Ber-EP4

Abstract

A 80-year-old man had noticed a tumor with bleeding in the anal region during evacuation. Physical examination revealed a 10 × 20 mm erythematous tumor accompanied by an ulcer on its surface at the 3 o'clock position of his anus. Additionally, there were blackdots in a part of the tumor. We excised the tumor surgically under local anesthesia, and we diagnosed it as basal cell carcinoma based on the histological findings and positive immunohistochemical staining for Ber-EP4. Perianal basal cell carcinoma is comparatively rare, and it presents a histopathological image similar to that of anal canal basaloid carcinoma. Anal canal basaloid carcinoma has the possibility of distant metastasis, thus we should be careful to differentiate perianal basal cell carcinoma from anal canal basaloid carcinoma.