Intestinal-type mucinous adenocarcinoma arising from the prostatic duct.

We present a case of mucinous adenocarcinoma of intestinal type arising from the prostatic duct in a 72-year-old Japanese man. The patient presented with macroscopic hematuria. Cystourethroscopy exhibited a mucus deposit at the 5 o'clock position of the verumontanum portion. A transurethral biopsy specimen revealed mucinous adenocarcinoma. A radical retropubic prostatectomy was performed. In the prostatectomy specimen, the cancer lesion mainly showed intraductal growth in the prostatic ducts with scattered mucin lakes in the prostatic stroma. There were no abnormalities in the urethral epithelium. The cancer cells resembled the intestinal epithelium rather than either the prostatic duct or the acinar epithelium, which showed diffusely positive immunohistochemical staining for carcinoembryonic antigen, but showed negative staining for prostate-specific antigen. Therefore, these findings suggest mucinous adenocarcinoma of intestinal type arising from the prostatic duct. A number of cases with mucinous adenocarcinoma arising from the prostatic urethra resembling the present case have been reported, but this is the first known case of carcinoma arising from the prostatic duct.