Liposarcoma is a common form of sarcoma in adults, mostly arising from the lower extremities and the retroperitoneum. However, primary liposarcoma of the mediastinum is an extremely rare tumor, accounting for 0.13% to 0.75% of all mediastinal tumors. These usually arise from the posterior mediastinum., Fewer than 150 cases have been reported in the medical literature. Primary liposarcoma of the pericardium, as described in this case, is one of the rarest forms of mediastinal liposarcoma., Although this may affect people aged between 9 months and 77 years, it is mostly a disease of adults. Presenting symptoms arise from compression of adjacent viscera and include dyspnea, cough, chest pain, and weight loss, but patients may also be asymptomatic. Obstruction of the superior vena cava may lead to superior vena cava syndrome. Patients can present with cardiac tamponade, acute pericarditis, chest wall involvement, metastases to other organs, syncope, or angina., Involvement of the lungs, aortic arch, atria, and pulmonary artery, by extension of the tumor, has been reported.