[X-ray features of primary non-squamous cell carcinoma and other malignant neoplasms in the trachea and main bronchi--analysis of 23 cases].

X-ray features of 23 cases (25 foci) of non-squamous cell carcinoma and other malignant neoplasms in the trachea and main bronchi were reviewed. They were 15 (17 foci) adenoid cystic carcinomas, 3 carcinoids, 2 mucoepidermoid carcinomas, 1 well-differentiated adenocarcinoma, leiomyosarcoma and extramedullary plasmocytoma each. The symptoms were non-specific leading to a delayed diagnosis more than one year in 52% of cases. The X-ray findings were classified into 3 types: intraluminal polypoid (11 tumors), sessile mass without and with extraluminal invasion (3 and 11 tumors). These tumors were prone to extraluminal invasion and can be demonstrated by X-ray. The air lumen involved appeared as localized expansion in 3 adenoid cystic carcinomas, 1 of which was proved by operation. Routine chest films were of limited value with 30% false negative chest film, 26% mediastinum mass and 30% obstructive pneumonitis/atelectasis. Lesions of posterior tracheal wall and carina were better revealed by lateral tomography. Of the 10 cases with lateral tomography, images were superior to those of AP tomography in 5. Three cases had CT scan, by which intra-tracheal/bronchial lesions, invasions of mediastinum and regional lymph nodes were shown. CT scan is more accurate compared with the other imaging modalities in visualizing these lesions and more helpful in selecting treatment.