A case of pulmonary artery intimal sarcoma diagnosed early using surgical biopsy

Abstract Background: Pulmonary artery intimal sarcoma (PAIS) is extremely rare and is very difficult to differentiate from pulmonary embolism (PE). Herein, we describe a case in which PAIS was strongly suspected based on clinical findings, and early definitive diagnosis was obtained.Case presentation: A 70-year-old man was referred to our hospital for the investigation of multiple round shadows in the lung fields and an enlarged right pulmonary hilar vasculature on chest radiography. Chest enhanced-computed tomography showed multiple pulmonary nodules, and bilateral non-contiguous shadows in the main pulmonary arteries, extending from the main pulmonary arteries to the periphery on the right side. Pulmonary embolism was clinically excluded because there were no subjective symptoms and the D-dimer level was normal. Positron emission tomography showed abnormal accumulation in the intrapulmonary arterial shadows, pulmonary nodules, and left iliac bone. The patient was clinically diagnosed with a suspected PAIS with multiple pulmonary and bone metastases within 3 days of presentation at our hospital. We performed a thoracoscopic partial resection of the right upper lobe and obtained a histopathological definitive diagnosis of PAIS. As the positive result for MDM2, we attempted to participate in the investigator-initiated clinical trial of anti-MDM2 antibody (DS-3032b) in patients with MDM2 amplified intimal sarcoma (JMA-IIA00402). However, he was not able to participate in the clinical trial due to the lack of MDM2 gene amplification by fluorescence in situ hybridization. He received drug therapy with cytotoxic anticancer agents, a multitargeted tyrosine kinase inhibitor, or an immune checkpoint inhibitor but it was ineffective, and he died nine months after definitive diagnosis.Conclusions: In actual clinical practice, it is important to make early clinical and histological diagnosis, always keeping in mind the possibility of rare lung malignancies.