Papillary adenocarcinoma of the epididymis.

An 82 year old man with a unilateral epididymal mass was found, on histopathologic examination of a surgically removed specimen, to have a primary papillary adenocarcinoma of a clear cell variant which mimicked renal cell carcinoma. Repeated imaging studies confirmed the absence of renal cell carcinoma. Because the present case had great similarities in histologic appearance and anatomical location to papillary cystadenoma of the epididymis, it may be a malignant counterpart of the latter type of tumor.