A case of primary lung leiomyosarcoma, which was treated surgically, is reported.Bronchoscopy revealed no endobronchial lesion, and malignant cells were nagative in the sputum. A biopsy material taken during surgery revealed nonepithelial malignant cells. These cells had oval to round nuclei displaying heavy, irregular chromatin patterns, and indentation of the nuclear border. A few spindleshaped giant cells were noted. Microscopic diagnosis of the resected material proved the tumor to have originated in the bronchial muscle of the left upper lobe bronchus. The main pathological and clinical features are discussed.
