Epstein-Barr virus-associated primary central nervous system lymphoma in the Japanese population.

The incidence of Epstein-Barr virus (EBV)-associated primary central nervous system (CNS) lymphoma in Japan was assessed using in situ hybridization of EBV-encoded small ribonucleic acid-1 (EBER-1) to identify the presence of EBV in 22 cases of formalin-fixed and paraffin-embedded primary CNS lymphoma. All cases were B-cell lymphoma. EBER-1 expression was observed in the nuclei of 3 of 22 primary CNS lymphoma cases (13.6%). The incidence of EBV-positive lymphoma in Japanese cases is higher than previously reported from Western countries. Patients with EBV-positive primary CNS lymphoma showed shorter survival than those with negative tumors (median 4 months vs. 26 months). EBER-1 in situ hybridization for the detection of EBV infection is rapid and reliable. Infrequent association suggests a different pathogenetic mechanism in the evolution of these tumors. Geographical differences in the incidence of EBV-associated primary CNS lymphoma may reflect epidemiological factors.