Endometrioid adenocarcinoma of the prostate: a clinicopathologic and immunohistochemical study.

On retrospective review of the tumor registry files between 1979 and 1992 at the North Iowa Medical Center, six cases of endometrioid adenocarcinoma of the prostate were identified among 1582 cases of prostatic carcinoma. Along with long-term clinicopathologic follow-up, immunohistochemical studies of the prostatic tumor tissues were performed. All six cases of endometrioid carcinoma, together with control cases of benign prostatic hypertrophy (BPH) and ordinary adenocarcinoma of the prostate had unequivocal diffuse positive staining for PSA and similar reactivity to ER-D5 and PS2. Thus, endometrioid carcinoma is most likely derived from the prostate or prostatic urethral duct rather than the utricle. However, due to its unusual initial clinical manifestations, biological behavior, and distinctive histomorphology, the term "endometrioid adenocarcinoma of the prostate" is worth preserving.