RESUMEN
Various types of sarcomas arise as a result of postradiation chronic fibrous pericarditis. A primary undifferentiated spindle cell pericardial sarcoma is a rare type of sarcoma after radiotherapy. The risk of sarcoma increases with time after treatment of cancer. A 55-year-old woman underwent successful radiation and chemotherapy for Hodgkin lymphoma 20 years ago. She was hospitalized with typical manifestations of severe heart failure. Echocardiography, Ñomputed tomography of the chest and magnetic resonance imaging scan of the heart detected neoplastic formations of the pericardium. A biopsy of the pericardium was performed. Histological, immunohistochemical, and genetic studies showed a primary undifferentiated spindle cell pericardial sarcoma (an extremely rare type of sarcoma).