Geographic variation in Epstein-Barr virus (EBV) association and frequency of LMP1 deleted variants in childhood lymphomas from Brazil and Argentina

VALVA, P.; GUIRETTI, D.; PAOLA ANDREA CHABAY; MAGALHÃES BARROS, M; DE MATTEO, E; KLUMB CE; ZALCBERG, I.; PRECIADO, M. V.; HASSAN, R.

San Salvador Bahia, Brasil

Congreso; X Brazilian Conference on Paediatric Oncology; 2006

Sociedad Brasilera de Oncología Pediatrica

Introduction: Childhood lymphomas are characterized by a marked variation across different geographic regions regarding age-specific incidence, clinical presentation and EBV association. We compared two groups of pediatric lymphoma patients diagnosed at single public institutions in Southeastern Brazil (Rio de Janeiro) and Argentina (Buenos Aires). Methods: Clinico-pathological characteristics and EBV association by ISH and PCR were analyzed in 41 Non-Hodgkin’s lymphomas, NHL, (25 Burkitt lymphoma, BL; 16 diffuse large B cell lymphoma, DLCBL) and 75 Hodgkin’s lymphoma (HL) from Argentina and 77 NHL (70 BL and 7 DLCBL) and 65 HL from Brazil. Results:  BL (Mn 6 years, 15m-16; M:F 2,3:1) and DLBCL (Mn 9 years, 2-16; M:F 1:1) from Argentina showed EBV association of  24% and 44% respectively, compared to BL (Mn 5 years, 2-14; M:F 2:1) and DLCBL (Mn 12 years, 4-16; M:F 6:1) from RJ-BR, with 62% and 71% respectively. Remarkably, all NHL in immunodeficient patients were EBV+ (N=7 from Argentina and N=5 from RJ, BR). Contrary to NHL, Argentine HL, Arg-HL, (Mn 8 years; 2-18; M:F 1,7:1) and Brazilian HL, Br-HL (Mn 14 years; 3-18; M:F 1,4:1) showed similar frequencies of EBV association (56 and 48% respectively). In Arg-HL, the mixed cellularity (MC) and nodular sclerosis (NS) histological subtypes were similarly represented (49 and 50%), while in Br-HL, 83% of the cases were NS followed by MC in 12.5%. EBV was more frequent in MC subtype (41/55, 75% in Arg-HL and 8/10, 87.5% in Br-HL). In Br-HL and Arg-HL 43 and 32% of NS cases were also EBV+. Analysis of LMP1 30bp deleted variant by PCR in 35 cases, showed that both HL groups differed in respect to the frequencies of deleted alleles, with 28% of Brazilian EBV+ cases carrying del(30pb) against 76% of Argentine cases. Conclusions: EBV association with NHL showed a clear geographic variation, with a higher number of Brazilian cases being positive. Concerning HL, even though the histological distribution is quite different, EBV association is similar. Although LMP-1 deleted variant was more prevalent in Arg-HL, its oncogenic role remains to be determined.