Extramammary Paget disease of the scrotum with features of Bowen disease - A case report and review of the literature

The scrotum is an uncommon site for the presentation of extramammary Paget disease (EMPD). We describe a case of EMPD that was discovered in a patient who had been previously diagnosed and treated for squamous cell carcinoma in situ of the scrotum 3 years earlier. Pathologic examination of the current scrotectomy specimen revealed an erythematous patch with areas of pale induration. Microscopic examination revealed areas with the characteristic histology of Paget disease adjacent to areas characteristic of Bowen disease. Immunohistochemical findings demonstrated a strong expression of carcinoembryonic antigen, cytokeratin 7, and low-molecular-weight cytokeratins (CAM 5.2) in both of these areas, giving support to the overall diagnosis of EMPD. High-molecular-weight cytokeratins (34betaE12) were uncharacteristically expressed in the cytoplasm of the Paget cells with equal or greater strength than in the surrounding keratinocytes, suggesting some degree of squamous differentiation. Very few publications have reported the coexistence of EMPD with squamous cell carcinoma in situ, occurring mostly in the vulva. To our knowledge, our case is the first report of scrotal EMPD with features of Bowen disease. Our findings support the theory that primary EMPD arises multifocally from multipotential epidermal cells.