Extraskeletal osteosarcoma of the pleura:report of a case.

Extraskeletal osteosarcoma is a rare malignant tumor occurring very rarely in the pleura. We herein report the case of 67-year-old man with asbestos exposure, who underwent biopsies of the large tumor from the chest wall, and diagnosed as a suspicious of fibrosarcoma. Surgical resection was done, and the pathological diagnosis was extraskeletal osteosarcoma arising from the pleura. The differential diagnosis is malignant pleural mesothelioma with osseous and cartilaginous which is also very rare and one of the histopathological subtypes with heterologous elements. Identification of epithelial components, labeling for cytokeratins in spindle cells and its' anatomical distribution may help to distinguish them. In the neoplasm arising from the parietal pleura, primary extraskeletal osteosarcoma of the pleura is very rare, but should be considered.