Pulmonary leiomyosarcoma appearing as a cyst. Report of one case and review of the literature.

We describe a case of pulmonary sarcoma appearing as a cyst in the lower lobe. A review of the literature on cavities and malignancies of the lung shows that lung cavities with a wall thickness of 4 mm or less were benign in 92% of the cases. After investigation, a basal segmentectomy was performed in the belief that the lesion was benign. Surprisingly, the histological examination demonstrated spindle-shaped tumor cells, and electron-microscopic studies showed myofilaments suggesting a leiomyosarcoma. This case report illustrates the diagnostic difficulties with lung cavities.