[A case of carcinosarcoma of the lung]

A 78-year-old man was admitted to our hospital with cough and left anterior chest pain. Chest X-ray examination on admission revealed a tumor shadow in the left upper lobe. Malignant tumor cells were observed on histopathological examination of a specimen obtained by bronchoscopic biopsy. Radiotherapy was performed but was not effective, and the patient died of respiratory failure 4 months after admission. Autopsy revealed a 15 cm diameter tumor with marked local invasion tendency without distant metastasis. Microscopically, the tumor consisted partly of squamous cell carcinomas, and partly of fibrosarcomas, composed of spindle cells and osteo-chondrosarcoma. The tumor was therefore diagnosed as carcinosarcoma. Immunohistochemical examination showed positive keratin and EMA staining only in the squamous cell carcinoma component of the tumor.