[Gingival Burkitt lymphoma in a hepatitis C-positive renal transplant patient].

Malignant tumors are a frequent complication in the late phase after organ transplantation. Malignant lymphomas are the second most common tumor, exceeded only by cutaneous carcinomas. Compared to the general population, the organ transplant patients have a 30-60 fold increased risk of developing non-Hodgkin's lymphoma. A 55-year-old, hepatitis C-positive man developed an Epstein-Barr virus (EBV)- negative Burkitt lymphoma (BL) first appearing on the gingiva under immunosuppressive therapy nine years after allogenic renal transplantation. He died 37 days after the onset of polychemotherapy. Immediately before his death, meningeal involvement by the BL was diagnosed. BL after organ transplantation is often found at extranodal sites; it involves the central nervous system more frequently than it does in immunocompetent patients. In 70% of BL occurring after organ transplantation, genes or gene products related to EBV can be demonstrated within the tumor cells. The EBV status of the tumor is of important prognostic significance: EBV-positive BL occurring in organ transplant patients usually responds well to reduction or cessation of immunosuppressive therapy; in some cases permanent complete remissions can be achieved even without chemotherapy. In contrast, patients with EBV-negative BL have a very poor prognosis and hardly respond, even to aggressive chemotherapy protocols.