18F-FDG PET/CT imaging of malignant PEComa originating in the pericardium: A case report.

Primary perivascular epithelioid cell tumors (PEComas) originating in the pericardium are extremely rare. We present a rare case of a malignant PEComa arising from the pericardium, with abnormal fluorine-18-fluorodeoxyglucose (18F-FDG) uptake maximum standardized uptake value (SUVmax 23.1) on positron emission tomography/computed tomography (PET/CT) scan, indicating its highly aggressive nature. Imaging revealed a soft tissue mass in the left atrial appendage with poorly defined borders to adjacent structures. The patient underwent CT-guided biopsy, and histopathological examination confirmed the diagnosis of malignant PEComa. This case underscores the atypical imaging features of a malignant pericardial PEComa, which, due to its elevated 18F-FDG uptake, should be considered in the differential diagnosis of cardiac masses with similar PET/CT characteristics, as well as for distinguishing between benign and malignant lesions.