Leiomyosarcoma of the pulmonary artery.

To the Editor:— Sarcomas originating in the pulmonary vasculature are rare, and 16 have been reported to date. None of these tumors was correctly diagnosed ante mortem or prior to thoracotomy. We wish to present an additional case because its almost perfect mimicry of a chronic embolus led to surgery. Report of a Case:— A 53-year-old white woman was first seen at an outside hospital in December 1963 with a one-year history of gradually increasing exertional dyspnea. Although a nonsmoker, she had had a productive cough for 15 years. Three days prior to being seen, markedly increased dyspnea, fever, and right sided pleuritic pain developed. A chest x-ray film revealed an infiltrate in the lower lobe of the right lung. With antibiotic therapy, she gradually improved, though x-ray film changes were slow to resolve. During the next seven months, the dyspnea progressed, and subsequent chest x-ray films revealed a small