Carcinosarcoma of the Lung

We describe a case of carcinosarcoma of the lung in a 60-year-old female who was admitted with complaints of productive cough and an abnormal shadow in the chest X-ray. Sputum cytology showed both squamous cell carcinoma and adenocarcinoma cells. Malignant nonepithelial cells were identified in the needle biopsy specimen. Right middle and lower lobectomy was performed to reveal a carcinosarcoma by microscopic and immunohistochemical examination. This case was histologically unusual because it presented multiple carcinomatous elements (squamous cell carcinoma and adenocarcinoma). It was classified as peripheral type according to the clinical classification, showing an extremely poor prognosis. The histogenesis and clinical features of this rare tumor are discussed.