Non Hodgkin Lymphoma (NHL) Distribution and Clinical Characteristics in a Mexican Registry with High Frequency of T Cell NHL: A Descriptive Study on Behalf of Mexican Hematology Study Group (MHSG).

Background: Among the NHL, B Cells NHL are more frequent than T Cells NHL (6%) as described in USA & European reports. The highest frequencies of T Cell NHL have been reported in Japan with 9% and India with 12%. In a Mexican retrospective study we found a T Cell NHL frequency of 13%.

Objective: To corroborate the patterns and frequency of B and T cell lymphomas in Mexico.

Methods: The registry of lymphoid neoplasms was created based on the WHO classification. The Lymphoma subtype analysis was prepared in two periods: retrospectively from 2002 to December 2005 and prospectively from January to December 2006. The data recorded were: age, sex, cell type (B o T), NHL frequency, primary site, stage and prognostic index (IPI and FLIPI).

Results: In the first group 2375 Lymphomas were included: 2122 B Cell NHL (89.34%) and 253 T-cell lymphomas 253 (10.6%). B-cell NHL: gender 55.17% male and 44.66 female, median age of 55.21 years Age >60 years 45.7%; 62% III–IV stage. After applying the FLIPI index, the patients were divided into three risk groups: low (8.4% of cases), intermediate (81%), and high (10.6%). The distribution of patients in IPI risk groups was 15.7%, 76%, and 8.3% of cases classified as low, intermediate, and high risk The frequencies of B cell lymphoma were: 49% DLBCL, 15% Follicular Lymphoma, 5.35% CLL/SLL, 1.6% Mantle cell Lymphoma, 0.9% Follicular Center Lymphoma, 1.6% Marginal Zone B Lymphoma, 6.1% MALT, 1.6% Burkitt Lymphoma. T cell lymphomas were distributed in: Peripheral T Cell 253 (46.36%), Cutaneous Anaplastic 42 (16.09%), T/NKcell 35 (13.40%), Lymphoblastic 28 (6.16%), T non classifiable 10 (3.83%). The second group included 344 lymphomas; 309 (89.82%) B Cell NHL and 31 (10.01%) T cell Lymphomas. Gender 51.7 male and 48.3 female, medium age 57.79 years (SD 16.09); . >60 years 44%. After applying the FLIPI index the distribution of patients was 24.5% with intermedium risk and 9.5.8% high risk. Patients were divided into three IPI risk groups: Low 69.2% Intermediate 23% and high risk 7.8%. The frequencies of B cell lymphomas subtype were: DLBCL 168 (52.3%), Follicular 58(18.4%), CLL/SLL 19 (6.14%), Mantle Cell 10 (3.2%), Follicle Center Lymphoma (0.9%), Marginal Zone B 4 (1.2%), MALT 14 (4.5%), Burkitt’s Lymphoma 5 (1.6%). The T Cell Lymphoma subgroup frequencies were: T Cell Peripheral 7 (22.5%), Cutaneous Anaplastic 5 (16.1%), N/K cell 4 (12.9), Lymphoblastic 3 (9.6%), T lymphoma non classifiable 6 (19%).

Conclusions: We confirmed a high incidence of T cell NHL in consecutive registries in Mexico. In the B cell subgroup it seems to be a difference where the DLBCL has a higher frequency and the CLL/SLL subgroup the lowest compared with other series. These differences in frequency might be explained by ethnic characteristics, however we need more epidemiological and viral studies, looking for Epstein Barr virus.