Primary Pulmonary Artery Sarcoma: Multimodality Imaging of a Rare Intravascular Tumor Mimicking Pulmonary Embolism

Primary pulmonary artery sarcoma (PPAS) is a mesenchymal tumor originating from the pulmonary artery, accounting for approximately 0.001-0.003% of all sarcomas. The early clinical symptoms are atypical, and diagnosis is often delayed, making the management of this disease challenging. The widespread availability of multidetector computed tomography (MDCT), ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT), and high-resolution echocardiography has significantly improved the diagnostic capability for PPAS. We herein report a 74-year-old female patient who presented with a 3-week history of exertional dyspnea without an apparent trigger. She had received anti-inflammatory therapy at another hospital for one week. Five days before admission, she experienced right-sided chest pain without apparent cause, which was respiratory-related. On the day of admission, laboratory tests revealed a slight elevation in D-dimer levels. Echocardiography showed an irregular, moderately echogenic mass at the origin of the right pulmonary artery. Enhanced computed tomography (CT) of the chest revealed a filling defect in the right pulmonary artery accompanied by bilateral pleural effusion. The patient was given heparin anticoagulation therapy. To confirm the nature of these lesions, a PET/CT scan was conducted five days after admission, which indicated hypermetabolism in the right pulmonary artery, suggesting primary pulmonary artery sarcoma. Due to the poor efficacy of anticoagulation therapy, the patient continued to experience breath-holding after physical activity. Subsequently, catheter-guided interventional angiography was carried out for pulmonary artery thrombectomy and biopsy, and histopathological examination revealed pulmonary artery sarcoma. Given the patient's respiratory failure and heart failure, as well as the uncertain efficacy of radiotherapy and chemotherapy, interventional pulmonary artery thrombectomy alleviated the chest pain. Currently, the patient's overall condition is stable.