Primary Cardiac Lymphoma Mimicking Cardiac Tumor: A Rare Case of Right Ventricular Mass With Seven-Year Remission.

Primary cardiac lymphoma (PCL) is an exceedingly rare extranodal lymphoma type that typically presents with nonspecific symptoms such as arrhythmias or heart failure. This report details the case of a 67-year-old male with a right ventricular mass, ultimately diagnosed as diffuse large B-cell lymphoma (DLBCL) of the germinal center B-cell (GCB) subtype. Initial chemotherapy with the CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen was insufficient, necessitating the addition of rituximab and subsequent mycophenolate therapy to manage immune thrombocytopenia. Through prolonged treatment and management of complications, the patient achieved remission and has remained disease-free over a seven-year follow-up period. This case highlights the diagnostic and therapeutic challenges of PCL, especially when associated with immune thrombocytopenia and suspected sternal osteomyelitis, underlining the importance of a multidisciplinary approach.