A Case of Primary Pulmonary Artery Intimal Sarcoma Leading to Right Heart Failure and Cardiogenic Shock: Diagnostic Challenges and Treatment Dilemmas

Background Pulmonary artery sarcoma (PAS) is a rare malignant tumor originating from the pulmonary arterial wall, often mimicking pulmonary thromboembolism. Echocardiography, computed tomography (CT), cardiac magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) are crucial for early detection. Case Presentation A 35-year-old man presented with dyspnea, signs of pulmonary embolism, and right ventricular (RV) strain. Echocardiography suggested pulmonary embolism with a suspected mass in the right ventricular outflow tract (RVOT). Despite thrombectomy and thrombolysis, the filling defect persisted. The initial biopsy was negative for malignancy. Further imaging with CT, cardiac MRI, and PET-CT revealed a fluorodeoxyglucose (FDG)-avid mass extending from the RVOT into the main pulmonary artery, causing significant stenosis. Subsequent pleural and lung video-assisted thoracoscopic surgery (VATS) biopsies were also negative. After four months, a third CT-guided biopsy confirmed a high-grade spindle cell neoplasm. Retrospective examination of the thrombectomy specimen revealed a small focus of atypical spindle cells with an identical immunohistochemical profile. The tumor was inoperable, and chemotherapy was not initiated due to severe cardiac symptoms. The patient ultimately developed circulatory shock and succumbed to his illness. Conclusion This case highlights the importance of early diagnosis and intervention in PAS to prevent fatal outcomes. While histopathology remains the gold standard, initial negative biopsies delay treatment. In suspected cases, a thorough examination of thrombectomy specimens, along with ancillary studies, is critical. Advanced imaging techniques, including cardiac MRI and PET-CT, may provide sufficient diagnostic evidence to initiate treatment when biopsy results are delayed or inconclusive.