Prostatic carcinosarcoma: case report and review of literature.

True carcinosarcoma of the prostate is a rare neoplasm, with only 9 cases well documented by immunocytochemistry and ultrastructural examination. We report a case of an unresectable pelvic tumor studied at autopsy. The primary prostatic neoplasm and pulmonary metastases were composed of well differentiated adenocarcinoma admixed with foci of leiomyosarcoma and osteosarcoma. The sarcomatous components showed reactivity with vimentin and desmin, did not express prostatic acid phosphatase (PAP) and prostate specific antigen (PSA), and contained myofilaments on electron microscopic examination. Positive staining of the carcinomatous component for PAP and PSA was noted. These findings confirm the mixed epithelial and mesenchymal components in primary and metastatic sites, and support the diagnosis of true prostatic carcinosarcoma.