Leiomyosarcoma of the pulmonary artery--a diagnostic chameleon.

A 60-year-old woman suffered from right-sided pain in the back and dyspnea suspicious for chronic pulmonary thromboembolism. Since computed tomography demonstrated a progressive filling defect within the left pulmonary artery, a transvenous biopsy was taken, which demonstrated malignant sarcoma. The patient underwent left-sided pneumonectomy with the aid of cardiopulmonary bypass. In case of a suspected 'chronic' pulmonary embolism with occlusion of a main pulmonary artery, as may be seen with imaging techniques, a sarcomatous disease should be ruled out, especially if there are no coagulation disorders, and the tumor obliterations progress in serial CT scans despite effective anticoagulation.