MALIGNANT-LYMPHOMA IN THAILAND - CHANGES IN THE FREQUENCY OF MALIGNANT-LYMPHOMA DETERMINED FROM A HISTOPATHOLOGIC AND IMMUNOPHENOTYPIC ANALYSIS OF 425 CASES AT SIRIRAJ-HOSPITAL

BACKGROUND. Analysis of malignant lymphoma in a single institution at different periods of time can determine the changing status of the dis ease in the region. METHODS. To compare with the large series of 1095 lymphoma cases reported between 1957-1971 at Siriraj Hospital, the lar gest hospital in Thailand, a similar study was performed through histo pathologic evaluation of 425 lymphoma cases diagnosed consecutively at the same institution between August 1993 and October 1995. Phenotypic analysis was performed by paraffin section-immunoperoxidase studies. RESULTS. A striking increase in lymphoma cases was noted from 73 cases /year in the first series to 189 cases/year in the second series (an i ncrease of 158.9%). Lymphoma occurred in all age groups, with a peak i ncidence at the seventh decade of life. The male to female ratio decre ased from 2:1 in 1957-1971 to 1.3:1 in the more recent series. The inc idence of Hodgkin's disease (HD) was found to have decreased from 28.9 % to 8.5%. There were 36 cases (8.5%) of HD and 389 cases (91.5%) of n on-Hodgkin's lymphoma (NHL) reported in the second series. The subtype s of HD included 16 cases of mixed cellularity, 13 cases of nodular sc lerosis, 6 cases of lymphocyte depletion, and 1 case of lymphocyte pre dominance. According to the Working Formulation, the 389 NHL cases inc luded low grade (14.1%), intermediate grade (57.3%), high grade (11.3% ), and miscellaneous groups (17.2%). They were classified as small lym phocytic (9.5%), follicular (11.1%), diffuse (50.9%), immunoblastic (4 .1%), small noncleaved (4.4%), lymphoblastic (2.8%), anaplastic large cell (9.0%), mycosis fungoides (1.8%), hairy cell leukemia (0.3%), tru e histiocytic (0.5%), and extramedullary plasmacytoma (1.0%). The immu nophenotypes of the 359 NHL cases available for paraffin section-immun operoxidase studies were B-cell (71.0%), T-cell (24.5%), histiocyte (0 .6%), and undetermined phenotypes (3.9%). CONCLUSIONS. The incidence o f malignant lymphoma is increasing in Thailand, with a high frequency of intermediate to high grade NHL of B-cell phenotype reported. (C) 19 98 American Cancer Society.