Pulmonary artery intimal sarcoma with predominantly peripheral arterial involvement and concomitant pulmonary thromboembolism: a case report

Background Primary pulmonary artery intimal sarcoma (PAIS), the predominant type of pulmonary artery sarcoma (PAS), is a rare, highly aggressive malignant mesenchymal tumor arising from the pulmonary arterial intima. PAS is usually indistinguishable from pulmonary thromboembolism (PTE), resulting in missed and delayed diagnosis and often leading to poor outcomes. In advanced disease, this condition may cause obstructive shock due to right ventricular failure, posing significant diagnostic and therapeutic challenges. Case Presentation A 53-year-old man presented with progressive exertional dyspnea, cough, and weight loss. Initial chest computed tomography demonstrated bilateral pulmonary arterial filling defects with pulmonary infarctions, leading to a diagnosis of PTE and anticoagulation therapy. Despite adequate anticoagulation, his symptoms progressively worsened. Follow-up computed tomography pulmonary angiography demonstrated interval enlargement of the pulmonary arterial filling defects, which showed heterogeneous enhancement and predominantly involved the left segmental and peripheral pulmonary arteries. Associated pulmonary artery expansion and a grape-like appearance raised suspicion for PAS. Following transfer to our institution, he developed severe hypoxemic respiratory failure and obstructive right ventricular failure requiring mechanical ventilation and vasopressor support. Histopathological examination of a transthoracic core needle biopsy confirmed PAIS with MDM2 amplification. The patient received palliative radiotherapy, one cycle of paclitaxel, and subsequent pazopanib therapy. Follow-up chest radiography demonstrated transient radiographic improvement, followed by both radiographic and clinical disease progression. He ultimately died from progressive disease. Conclusions This case highlights the diagnostic challenge of distinguishing PAIS from PTE. Prompt recognition of the characteristic imaging findings of PAIS, including heterogeneous enhancement, pulmonary artery expansion, and the grape-like sign, is particularly important in patients who do not respond to anticoagulation therapy. Early recognition and timely tissue diagnosis are essential to facilitate appropriate multidisciplinary management.