Pulmonary artery intimal sarcoma mimicking chronic thromboembolic pulmonary hypertension: a case report and diagnostic challenge

Abstract Background Pulmonary artery intimal sarcoma (PAIS) is an exceptionally rare and aggressive mesenchymal malignancy arising from the intimal layer of the pulmonary artery. Owing to its nonspecific clinical manifestations and radiologic resemblance to pulmonary thromboembolic disease, delayed diagnosis is common. Case presentation We report the case of a 38-year-old male who presented with progressive dyspnea, pleuritic chest pain, and hypoxemia. Computed tomography pulmonary angiography initially demonstrated bilateral saddle-shaped pulmonary arterial filling defects, and the patient was treated for presumed acute pulmonary embolism with anticoagulation. Despite adequate anticoagulation, clinical and radiological deterioration occurred, prompting subsequent evaluation for presumed chronic thromboembolic pulmonary hypertension (CTEPH). Echocardiography revealed pulmonary hypertension with preserved ventricular function. The patient underwent pulmonary endarterectomy for presumed operable CTEPH. Intraoperatively, the obstructive lesion appeared mass-like rather than thrombotic. Histopathological examination demonstrated a high-grade spindle cell sarcoma. Immunohistochemistry demonstrated positivity for MDM2 and CDK4 and negativity for SMA, CD31, and S100, supporting the diagnosis of pulmonary artery intimal sarcoma. Subsequent 18 F-FDG PET/CT demonstrated metabolically active lesions involving the pulmonary artery and its branches, with additional peri-pulmonary and mediastinal lesions. The patient was referred for multidisciplinary oncologic management and started on gemcitabine plus docetaxel chemotherapy. Conclusion PAIS is a rare but important differential diagnosis of pulmonary embolism and presumed CTEPH, particularly in patients with progressive symptoms or persistent pulmonary arterial filling defects despite adequate anticoagulation. Early recognition and multimodal evaluation may facilitate appropriate diagnosis and multidisciplinary management.