Prostate cancer presenting with malignant ascites: signet-ring cell variant of prostatic adenocarcinoma.

A case of prostate cancer presenting with malignant ascites as the sole clinical manifestation is reported. The clinical course simulated occult gastrointestinal malignancy. At the histologic level, the tumor had a signet-ring morphology. Detailed immunocytochemical and ultrastructural studies, however, confirmed the prostatic origin of this neoplasm. Signet-ring carcinoma of the prostate is a rare aggressive form of prostatic cancer which may present with a malignant effusion and may mimic gastrointestinal cancer.