Because of its rarity and insidious growth characteristics, pulmonary artery sarcoma is often mistaken for pulmonary embolism,11–12 leading to inappropriate therapy such as prolonged anticoagulation or thrombolysis. The need for a precise preoperative diagnosis is crucial for the proper exploration of the pulmonary artery to ensure complete resection and reconstruction. Symptoms and signs such as weight loss, fever, anemia,13–14 and digital clubbing15–16 may be subtle clues to diagnosis. Other characteristics, such as the absence of risk factors for deep vein thrombosis, high sedimentation rate, nodular parenchymal infiltrates on CT scans, unilateral absence of blood flow on perfusion scan, and lack of response to anticoagulation should raise the suspicion of a process other than pulmonary embolism. Unfortunately, none of the above features can exclude the possibility of chronic thromboembolic disease. Enhancement of an intraluminal filling defect with gadolinium-diethylenetriamine pentaacetic acid on MRI has been suggested as a sensitive way of differentiating a tumor mass from a thrombus.17–20 Multiplane transesophageal echocardiography21and fluorodeoxyglucose positron emission tomography22have been used as preoperative diagnostic tools. Positron emission tomography has the added advantage of diagnosing indeterminate hilar masses. Other novel diagnostic methods currently being refined include the use of a transvenous catheter suction biopsy23 and pulmonary angioscopy, which was performed in our case.