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Epstein–barr virus in diffuse large B‐Cell lymphoma in immunocompetent patients in Japan is as low as in Western Countries

According to previous reports, the frequency of Epstein–Barr virus (EBV) positivity in diffuse large B‐cell lymphoma is higher in East Asia (approximately 9%) than in Western countries. The presence of the EBV genome was examined in diffuse large B‐cell lymphoma patients registered with the Osaka Lymphoma Study Group (OLSG) in Osaka, Japan, situated in East Asia. The EBV‐positive rate was examined with in situ hybridization (ISH) in 484 immunocompetent diffuse large B‐cell lymphoma patients registered with OLSG. The male‐to‐female ratio was 1.29, with ages ranging from 16 to 95 (median, 68) years. ISH with EBV‐encoded small RNAs (EBER) probes revealed positive signals in the nuclei of tumor cells: the frequency of positively stained cells among all tumor cells was almost none in 458 cases, 5–10% in 5, 10–20% in 5, 20–50% in 11, and >50% in 5. When the frequency was >20% or >50%, the EBV‐positive rate in the present series (3.3% or 1.0%) was rather similar to that reported in Western cases. Careful evaluation of patient backgrounds, including age distribution, type of lymphomas, exclusion of immunocompromised patients, and establishment of definite criteria for EBV positivity (>20%, >50%, or almost all tumor cells) are essential in comparing geographical differences. J. Med. Virol. 83:317–321, 2011. © 2010 Wiley‐Liss, Inc.