Heterologous sarcomatoid pleural mesothelioma with osteosarcomatous differentiation: a report of autopsy case that accomplished trimodality therapy and review of the literature.

Heterologous mesothelioma is a very rare subtype of sarcomatoid mesothelioma characterized by the presence of malignant heterologous elements. A 69-year-old man with a strong history of asbestos exposure presented with a 5-cm mass in his chest wall, destroying the right 5th rib and spreading along the parietal pleura, on a CT. Biopsy revealed heterologous mesothelioma with osteosarcomatous elements, following which left extrapleural pneumonectomy was performed with combined resection of pericardium, hemidiaphragm, and 4th, 5th, and 6th costal segments. A small cytokeratin-positive epithelioid component in the resected tumor definitively confirmed the diagnosis. Post-operative chemotherapy and intensity-modulated radiotherapy were undertaken. After 12-month disease-free period post treatment, rapid intraperitoneal recurrence resulted in death. Autopsy revealed no tumors in the left thorax. We present here a case of heterologous osteosarcomatous pleural mesothelioma that followed a unique clinical course after trimodality therapy. In addition, literature of 54 cases of the similar heterologous mesothelioma was reviewed.