A 26-year-old patient with a voluminous primary pulmonary hemangiopericytoma in the right lung, diagnosed through previous surgical biopsy, presented irreversible cardiac arrest during the hilar dissection portion of a right pneumonectomy. The patient did not respond to resuscitation efforts. Autopsy showed total obstruction of the mitral valve by a tumor embolism. In cases of large lung masses with hilar involvement, as in the case presented, we recommend preoperative evaluation using transesophageal echocardiography, magnetic resonance imaging or angiotomography. If injury to the pulmonary vessels or atrial cavities is detected, surgery with extracorporeal circulation should be arranged in order to allow resection of the intravascular or cardiac mass, together with pulmonary resection. We recommend that care be taken in order to recognize and treat this problem in patients not receiving a preoperative diagnosis.