Fewer than 300 patients with primary pulmonary artery sarcoma have been reported since 1923, when it was first described by Mandelstamm.¹The diagnosis of pulmonary artery sarcoma is difficult, and misdiagnosis as chronic pulmonary embolism often occurs. Herein, we reported a case of primary pulmonary artery chondrosarcoma. So far as we know, this patient served as the first case ever reported to receive computed tomography pulmonary angiography (CTPA), gadolinium enhanced magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) before surgery. By these means, the utility of different imaging modalities for pulmonary artery sarcoma was well demonstrated.

A 58-year-old female with progressive dyspnea for six months, despite one month of anticoagulation therapy with rivaroxaban for chronic pulmonary embolism, was transferred to our hospital. Physical examination revealed a Grade 4/6 systolic ejectionmurmur at the left sternal border. Blood gas analysis was normal with pO²of 85 mmHg and pCO²of 35 mmHg. Because this patient had no history or risk factors of thrombosis, and was refractory to anticoagulation therapy, the possibility of tumor was suspected.

Transthoracic ultrasound echocardiography was performed, revealing a 41 mm×22 mm heterogeneous echo lesion within the main pulmonary artery and the outflow tract of the right ventricle. Systolic pulmonary artery pressure was estimated to be 109 mmHg. CTPA showed a low-attenuation filling defect with multiple calcifications within the main and right pulmonary artery (Figure 1A and 1B). However, CT venography of the lower extremities was negative for deep vein thrombosis. To further detect the lesion, this patient received cardiovascular MRI, which demonstrated an isointensity T1WI and hyperintensity T2WI mass filling the lumen of the main pulmonary artery, the right pulmonary artery, and the outflow tract of the right ventricle. The posterior leaflet of the pulmonary artery valve was also infiltrated (Figure 1C). After intravenous gadolinium injection the mass showed heterogeneous enhancement (Figure 1D). Moreover, increased fluorodeoxyglucose (FDG) uptake within the mass was detected by PET/CT scan, with maximum standard uptake value (SUV) of 3.8, which highly suggested the malignancy quality of this mass (Figure 1E).

Open thoracotomy was performed with total cardiopulmonary bypass. A whitish-gray, myxoid mass was found to occupy almost the whole lumen of the main and right pulmonary artery. It infiltrated the posterior leaflet of the pulmonary artery valve, and the outflow tract of the right ventricle as the MRI images had revealed. A curative pulmonary artery mass resection and pulmonary valvuloplasty were performed. Histopathological examination was consistent with primary pulmonary artery chondrosarcoma (Figure 1F). Immunohistochemical staining was positive for vimentin, and negative for desmin. A repeated CTPA 5-day postoperatively was unremarkable. The patient declined adjuvant chemotherapy or radiotherapy, and had no further discomfort during six months of follow-up.

The prevalence of primary cardiac malignant tumors is estimated at only 0.001% to 0.28%.²As a subclassification of primary pulmonary artery sarcoma, primary pulmonary artery chondrosarcoma are even more rare, and are presumed to arise from multipotential mesenchymal cells of the muscle angle of the bulbus cordis.³The clinical symptoms and imaging signs of this tumor are very similar to those of chronic pulmonary embolism. As a result, misdiagnosis often occurs, and anticoagulation therapy is given. This will delay the surgery, and complicate the outcome. Although there is no agreement on the treatment of primary pulmonary artery sarcoma, it is suggested that surgical resection combined with adjuvant chemotherapy or radiotherapy might be a better choice. Longer median and 5-year survival has been reported in patients with curative resection, compared with a palliative resection group.³