We present a case of a 66-year-old male with dyspnea and bilateral lower-extremity edema. Pericardiotomy and biopsy were performed and reported malignant mesothelioma. Primary pericardial mesothelioma is a highly malignant tumor that has unfavorable prognosis, and is extremely rare, even among heart tumors. In our case, despite the large amount of pericardial effusion of the first echocardiography, the infiltrated like pericardium was still detected. In addition, cytology after pericardiocentesis reported suspicion of malignancy, which followed by pericardiotomy and biopsy, lead to our timely diagnosis.

A 66-year-old male referred to our hospital with dyspnea and bilateral lower-extremity edema. Chest radiography (CXR) showed pleural effusions and cardiomegaly. Transthoracic echocardiography revealed large pericardial effusion with a heterogeneous hyperechoic mass in the right ventricular pericardial wall. Histopathological examination confirmed the diagnosis of epithelioid mesothelioma. Primary pericardial mesothelioma is an extremely rare and poorly diagnosed malignancy with a historically poor prognosis. Thus, a timely diagnosis and treatment are crucial for the management of primary pericardial mesothelioma.