Extraskeletal osteosarcoma of the pleura: a case report.

We herein present an exceedingly rare case of pleural osteosarcoma that was surgically resected in an elderly patient. A 74-year-old man, complaining of a dry cough and breathlessness on effort, was found to have massive pleural effusion on a chest X-ray. The chest CT and MRI scans indicated a massive effusion and a pleural tumor encasing the left lower lung. The resected tumor was histologically an osteosarcoma, measuring 11.3 x 9.0 x 6.0 cm. Because there was no evidence of any other primary tumor, the diagnosis of extraskeletal osteosarcoma was appropriate.