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Diagnosis and management of persistent pulmonary thromboembolism.

Despite anticoagulation therapy, however, his symptoms failed to resolve. A repeat CT angiogram (Fig 2) was performed 1 month later and showed that the mass within the pulmonary artery trunk was increasing in size. It extended from 1 cm above the pulmonic valve into the proximal portion of the left pulmonary artery and into the first division of the right pulmonary artery, with near total occlusion of the right pulmonary artery. On further workup, transesophageal echocardiography (TEE) (Fig 3) revealed an echogenic mass within the proximal pulmonary trunk, with a pedunculated portion of the mass that was mobile with cardiac contraction. This mass did not involve the right ventricular outflow tract but extended distally into the right pulmonary artery. Left and right ventricular functions were normal. Mild tricuspid valve regurgitation was present. Doppler measurement of the regurgitant jet estimated systolic right ventricular pressure at 63 mmHg, suggesting severe pulmonary hypertension. A cardiac magnetic resonance imaging (MRI) scan confirmed these findings (Fig 4). Quantitative pulmonary radionuclide scanning revealed only 11% perfusion to the right lung. What is the differential diagnosis for this mass in the pulmonary artery?