[Composite carcinoma of the prostate combining a small cell carcinoma and an adenocarcinoma. Apropos of a case].

A case of combined adenocarcinoma and small cell carcinoma of the prostate is described in a 58-year-old-man. Prostatic acid phosphatases and neuron specific enolase were found elevated in the serum. At autopsy the lung was free of tumor. The liver was replaced by numerous metastatic nodules and a voluminous mesenteric metastasis extended into the wall of the vessels (aorta and vena cava). Microscopic examination showed a small cell carcinoma component of the oat cell type and an adenocarcinoma component constituting 10% of the total tumor volume. By immunostaining, the small cell carcinoma component is neuron specific enolase+ and prostatic specific antigen-. The adenocarcinoma component is neuron specific enolase- and prostatic specific antigen+.