Epstein-Barr virus frequency in primary central nervous system lymphomas in Turkey

Primary central nervous system (CNS) lymphomas are rare neoplasms which are usually not associated with Epstein-Barr virus (EBV) in immunocompetent patients. The aim of this study was to investigate the incidence of EBV in primary CNS lymphomas in the Turkish population. Thirty-two primary CNS lymphomas diagnosed according to the WHO 2008 criteria were included in this study. The presence of EBV small ribonucleic acids was investigated by in situ hybridization using EBV encoded small RNA oligonucleotides. The expression of CD10, Bcl-6, MUM-1/IRF-4, Bcl-2, and Ki-67 were evaluated using immunohistochemistry. The patient cohort included 20 male patients and 12 female patients with a median age of 53.5 years (range 13-75). Seven (22%) of cases were classified as germinal center (GC) and 25 (78%) cases as non-GC phenotype according to the Hans criteria. Twenty-six (81%) of the cases showed strong Bcl-2 expression and the median Ki-67 index was 78%. EBV expression was observed in four primary CNS lymphoma cases (12.5%). Most primary CNS lymphomas show non-GC phenotype with high Bcl-2 expression and high proliferative rate. The incidence of EBV in primary CNS lymphomas from Turkey appears to be higher than that observed in the Western countries.