Intraductal carcinoma of the prostate metastatic to the penile urethra: a rare demonstration of two morphologic patterns of tumor growth.

Penile metastases from prostate cancer are rare and are usually a manifestation of wide-spread cancer dissemination. Isolated urethral metastases form a small fraction of these cases, have a longer survival rate and may represent spread by implantation following instrumentation. We report a case of prostatic carcinoma presenting with an isolated metastasis to the penile urethra after catheterisation and transurethral prostatectomy. The primary tumor had a prominent intraductal component whose architectural features were mimicked in the metastasis. The possible mechanisms of spread and the diverse appearances of cancer associated with an intraductal component are discussed.