We present an eighty-three-year-old man with an exophytic lesion in the prostatic cavity, diagnosed three years after transurethral resection of the prostate, and extending into the bladder. Histopathologically, the tumor was recognized as a papillary ductal adenocarcinoma (primary duct type) with endometrioid features, probably associated with prostatic adenomatous polyp. Acinic adenocarcinoma was absent. The lesion was treated by deep transurethral resection with objective follow-up results after six months. Review of the literature concerning history, embryology, possible pathogenesis, differential diagnosis, and treatment options is included.