Biopsy revealed sarcomatoid mesothelioma, the rarest subtype of mesothelioma (the others being epithelioid and biphasic). Spindle-cell mesothelioma, sarcomatous and diffuse malignant fibrous mesothelioma are other names for sarcomatoid mesothelioma. It accounts for approximately 10 % of pulmonary mesothelioma. Histologically, the findings are similar to histiocytoma. It contains spindle cells and must be differentiated from sarcoma.