A Comprehensive Collaborative Nationwide Lymphoma Study in Lebanon: Incidence of Various Subtypes and Analysis of Associations with Viral Infections

Abstract

5220 Background: lymphoid neoplasms represent a diverse group of neoplasms that are broadly classified into non-Hodgkin lymphomas (NHL) and Hodgkin lymphoma (HL). Incidence of particular subtypes and pathogenic associations with certain viral infections are derived from data from the Western world. Little is known about such associations in developing countries; accordingly, this prospective study evaluates newly diagnosed cases of lymphomas in Lebanon and evaluates the incidence of particular subtypes and possible association with various viral infections. Patients and Methods: this was a collaborative nationwide study that included all patients diagnosed with lymphoma in Lebanon in 2007. Epidemiological, clinical and histological data were collected. Available lymphoma tissue (stained slides and paraffin-embedded tissue) was reviewed by a panel of pathologists. Blood was collected for serologic testing for the following viruses: hepatitis C (HCV), HIV, EBV, and HTLV-I. Results: 275 cases, 140 (50.7%) males and 136 (49.3%), with lymphoma were diagnosed. Eighty one cases (76 from academic centers and 5 from community hospitals) were reviewed by the pathology panel. The overall concordance rate was 87.6% (71/81); there was discordance in 6 (7.4%) cases: 3 originally diagnosed as diffuse large B cell lymphoma (DLBCL) were revised to high-grade follicular lymphomas, 1 small lymphocytic lymphoma (SLL) previously DLBCL, 1 DLBCL previously low grade lymphoma, 1 DLBCL previously lymphoblastic lymphoma; 4 cases were considered equivocal on revision. The enrolled cases were classified as follows: 183(66.5%) NHL (150 cases B cell lymphoma - 81 DLBCL, 35 follicular, 12 marginal zone/MALT, 11 mantle cell, 7 SLL/CLL, 2 transformed follicular/DLBCL, 2 lymphoblastic; 16 cases T cell lymphoma - 7 peripheral T cell NOS, 4 anaplastic, 2 lymphoblastic, 1 angioimmunoblastic, 1 NK cell, 1 adult T cell leukemia/lymphoma (ATLL); 17 unclassified); and 92(33.5%) HL (60 nodular sclerosis, 5 mixed cellularity, 5 lymphocyte predominant, 1 lymphocyte-rich, 21 unclassified). Blood was obtained from 120 patients. Serology was negative for HCV in all tested cases. HIV was positive in 2 cases (1 NHL, 1 HL). EBV IgG were positive in 106 (88.3%) cases (68/77 NHL, 38/43 HL). Also, 38 EBV seropositive cases (27 NHL (24 B-cell type & 3 T-cell type), 11 HL) were studied for latent membrane protein-1 (LMP-1); LMP-1 staining was positive in 8(21%) cases, of which 6 were HL and 2 were T-cell NHL. Only one case with peripheral T cell lymphoma (ATLL) tested positive for HTLV-1. Conclusions: our epidemiological study showed that two-thirds of lymphoma cases diagnosed over a year were NHL. Reviewing almost one-third of cases showed an 87.6% concordance rate in diagnosis. Serologic testing of viruses did not reveal any specific pattern that suggests an association between the tested viruses (HCV, HIV, EBV, and HTLV-I) and lymphoma. However, LMP-1 testing was positive in 54.5% of IgG positive HL cases and in 66.7% of IgG positive T-cell NHL. These finding confirm a strong association of EBV with HL and T-cell lymphoma. Disclosures: Bazarbachi: Hoffman La Roche: Research Funding.