In a review of pulmonary tumors diagnosed at our institute from 1976 t
o 1995, we found 20 malignant and 12 benign rare tumors, which account
ed for 0.57 and 0.34% of all pulmonary tumors, respectively. The histo
logical types of these rare malignant tumors were malignant lymphoma (
6/20), carcinosarcoma (3/20), mucoepidermoid carcinoma (2/20), bronchi
al gland mixed tumor (2/20), adenocystic carcinoma (1/20), myoepitheli
oma (1/20), leiomyosarcoma (1/20), epitheloid hemangioendothelioma (1/
20), hemangiopericytoma (1/20), malignant melanoma (1/20) and chorioca
rcinoma (1/20). Benign rare tumors involved papilloma (3/12), lipoma (
3/12), leiomyoma (3/12), adenoma (1/12), fibroma (1/12), and meningiom
a (1/12). The clinical and pathological features of malignant tumors w
ere roughly the same as those of common pulmonary carcinomas. In contr
ast, benign tumors were never larger than 3 cm and were more commonly
located in the central parts of the lung, which explained the relative
ly frequent symptoms of wheezing and fever associated with obstructive
pneumonia.