Primary signet ring cell carcinoma of the prostate: report and review of 42 cases.

We report a case of primary signet ring cell carcinoma of the prostate in a 75-year-old man. Serum prostate specific antigen (PSA) level at presentation was 9.3 ng/mL. The tumor was confined within the right prostate lobe and the patient was treated with neoadjuvant hormonal therapy and radical prostatectomy. He was alive with no evidence of disease 12 months after surgery. None of the tumor was stained with periodic acid-Schiff and Alcian blue. Immunohistochemically, the tumor was positive for PSA and prostatic acid phosphatase and negative for carcinoembryonic antigen. We reviewed 41 previously reported cases of signet ring cell carcinoma of the prostate, examining both histopathological and clinical information.