[True pulmonary carcinosarcoma suspected as a metastatic lung tumor].

This patient, a 53-year-old man, has underwent operation on the diagnosis of esophageal cancer 2 years ago. An abnormal shadow was detected in the left lung field and he was admitted to our hospital for further examination. On the suspicion of metastatic lung tumor by transbronchial brushing cytology, partial resection of the left lower lobe was performed. Histologically the tumor was of carcinomatous (squamous cell carcinoma and adenocarcinoma) and sarcomatous (fibrosarcoma and chondrosarcoma) elements, so the patient was diagnosed as "true" pulmonary carcinosarcoma. True pulmonary carcinosarcoma is one of the very rarest neoplasms of the lung.