Carcinosarcoma of the lung mis-diagnosed preoperatively as a mediastinal tumor

Carcinosarcoma of the lung is an uncommon tumor and is rarely preoperatively correctly diagnosed. The prognosis of patients with carcinosarcoma is extremely poor, despite treatment. A 79-year-old man was mis-diagnosed preoperatively as having a malignant mediastinal tumor. Excision of the tumor with segmentectomy of the lung revealed it was composed of a variety of carcinomatous and sarcomatous elements, which is a clear manifestation of the histogenetic totipotentiality of carcinosarcoma. He was subsequently treated with adjuvant chemotherapy and irradiation. He remains well at sixteen months after the operation, to date. Here we report this rare true case of a carcinosarcoma, focusing on the difficulty of a correct preoperative diagnosis.