[Pleural malignant mesothelioma with osseous cartilaginous and rhabdomyogenic differentiation].

A 63-year-old man, who was formerly an asbestos factory worker who had been followed due to asbestosis, and was admitted to our hospital with left chest pain and dyspnea on exertion. A chest X-ray and chest computed tomogram (CT) on admission revealed a large tumor in the left lung field. Percutaneous needle biopsy determined that the tumor was a sarcoma. No clinical response was obtained by systemic chemotherapy. The autopsy revealed diffuse malignant mesothelioma of sarcomatous type with osseous, cartilaginous and rhabdomyogenic differentiation. Osseous and cartilaginous differentiation in a malignant mesothelioma is rare, and the presence of a malignant rhabdomyogenic component is the first to be described in the Japanese literature.