Thijs, L. G., Kroon, T. A. J., and van Leeuwen, Th. M. (1974).Thorax, 29, 490-494. Leiomyosarcoma of the pulmonary trunk associated with pericardial effusion. The case history of a patient with a leiomyosarcoma of the pulmonary trunk is presented. The clinical picture was dominated by unexplained shortness of breath, episodes of cough and haemoptysis, general weakness, and weight loss. Signs of a pericardial effusion and pulmonary stenosis developed a few weeks before death. Thoracotomy revealed an inoperable tumour arising from the pulmonary trunk and a large pericardial effusion. Microscopy of the tumour removed at necropsy showed a leiomyosarcoma.