Pulmonary artery sarcoma is an extremely rare cause of pulmonary artery obstruction. Because of its similarity in clinical presentations and radiographic findings to pulmonary thromboembolism, the tumors are frequently misdiagnosed and its true incidence is probably underestimated. Herein, we describe a patient with a presumptive diagnosis of chronic pulmonary thromboembolism who was later found to have pulmonary artery sarcoma. We also review the distinguishing clinical and radiographic characteristics of the 2 diseases.