A Case of Concurrent Extramammary Paget Disease and Basal Cell Carcinoma of the Perianal Region.

An 83-year-old Japanese man who had been aware of a tumor near his anus for 2 years underwent tumor resection. Although he was diagnosed with basal cell carcinoma (BCC), extramammary Paget disease (EMPD) was also accidentally found in the same specimen. In the pathological histology of EMPD, there were large round cells with ample cytoplasm spread in the epidermis; these cells were positive for cytokeratin 7 and gross cystic disease fluid protein 15. No signs that are typically associated with EMPD, such as erythema or leukoderma, were observed near the anus. There have been only 4 reports in which BCC and EMPD developed in the same area, and the authors present the fifth case. In the reported case, no clear evidence was found for the corelative development of BCC and EMPD.