Pulmonary artery intimal sarcoma with pleural effusion: a case report

Background: Pulmonary artery intimal sarcoma (PAIS) is a rare and aggressive malignancy that is frequently misdiagnosed as pulmonary thromboembolic disease because of overlapping clinical and imaging features. Case presentation: A 52-year-old woman was admitted in September 2025 due to progressive dyspnea, pleural effusion, and elevated D-dimer levels. Imaging analysis suggested potential pulmonary embolism, and thoracoscopic pleural biopsy and endovascular sampling revealed no evidence of malignancy. The persistent obstruction of the pulmonary artery, the absence of an identifiable thromboembolic source, and atypical angiographic findings raised the suspicion of an underlying malignant process. A repeat pulmonary angiography, accompanied by targeted endovascular biopsy, identified a spindle cell tumor with myxoid degeneration. Immunohistochemical and molecular analyses corroborated the diagnosis of PAIS. She experienced temporary symptomatic improvement following interventional treatment and subsequently underwent surgical pulmonary artery tumor endarterectomy. The postoperative course was uneventful. Conclusion: This case highlights the diagnostic challenges associated with PAIS and underscores the importance of considering PAIS in the differential diagnosis of pulmonary thromboembolic disease, particularly in patients with atypical pulmonary artery lesions and inconclusive initial investigations.