RESUMEN
Papillary adenocarcinoma of the prostate, previously referred to as endometrioid carcinoma, is a variant of prostatic adenocarcinoma. Clinical and pathological evidence of involvement of the periurethral prostatic duct or verumontanum is usually required for definitive diagnosis of papillary adenocarcinoma. However, significant histologic and clinical features of papillary adenocarcinoma overlap with typical acinar carcinoma. Four cases of papillary adenocarcinoma were studied for the clinical features, histologic characteristics and immunohistochemical nature of prostatic specific antigen. In two cases, there were papillary regions, near the verumontanum, but in the other two cases, there were no papillary regions in the urethra. In two cases, acinar adenocarcinoma coexisted with papillary adenocarcinoma. All cases displayed positive immunohistochemical staining for prostatic specific antigen. In accordance with the observations of others, we suggest that papillary adenocarcinoma is one aspect of growth pattern of acinar adenocarcinoma, not a concept of a unique clinical and pathological entity.