Signet ring cell differentiation in adenocarcinoma of the prostate: a study of five cases.

Signet ring cell differentiation in adenocarcinoma of the prostate is uncommon. In a review of 200 cases of prostatic carcinoma, we identified five cases with this change, all in moderately to poorly differentiated prostatic carcinomas. The signet ring cells in prostatic carcinoma contain an intracytoplasmic lumen, shown on electronmicroscopy to be lined by microvilli. Transition stages were seen from solid to acinar to signet ring cells to mucinous variants. We believe that this change is part of the spectrum of appearances of prostatic carcinoma and should not be regarded as a subtype of specific significance.