Localized malignant pleural sarcomatoid mesothelioma misdiagnosed as benign localized fibrous tumor.

Localized malignant pleural mesothelioma (LMPM) is a rare tumor with good prognosis by surgical resection. We report an atypical case of malignant pleural sarcomatoid mesothelioma (SM) in an asymptomatic 65-year-old woman, who had no history of exposure to asbestos. She presented with a small pleural mass without pleural effusion and was misdiagnosed as a benign localized fibrous tumor (BLFT) on pathologic examination through a surgical tumor specimen.