A case report of pulmonary artery intimal sarcoma negative for 18F-FDG mimicking pulmonary thromboembolism

Background Pulmonary artery sarcoma is a rare malignant neoplasm arising from intimal mesenchymal cells in the pulmonary artery wall and is often difficult to differentiate from pulmonary embolism, however, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be useful for a differential diagnosis. Here, we present a rare case of pulmonary sarcoma undetectable by PET. Case summary A 77-year-old woman who had worsening dyspnoea on effort for a month and progressive chest discomfort with nocturnal cough for a week presented to our hospital. Contrast-enhanced computed tomography (CT) demonstrated a massive filling defect in the left pulmonary artery (PA). Two major differential diagnoses were considered; pulmonary thromboembolism and tumour-like lesions. Positron emission tomography-computed tomography (PET-CT) revealed that there was no abnormal accumulation of 18F-FDG in the mass. However, even after effective anti-thrombotic treatment for 3 weeks, a follow-up CT showed no reduction at all in the size of the lesion in the pulmonary artery. Therefore, surgery for diagnostic therapeutic purposes was performed. Discussion The present case is informative because it supports the idea that being aware of PA angiosarcoma as a potential differential diagnosis of pulmonary thromboembolism is essential, particularly in cases of no evident peripheral venous thrombosis and a negative D-dimer test, even if neither heterogenous contrast enhancement in CT and magnetic resonance imaging nor accumulation of 18-FDG in PET-CT is evident.