The Relative Frequency Of The Different Lymphomas

Inevitably, in any discussion of lymphoma classification there tends to be greater emphasis on the rare and difficult conditions than is necessarily warranted by their frequency. Because of epidemiologic differences and regional bias, it is difficult to generalize about the distribution of different lymphomas. Extrapolating from previous studies that preceded the REAL classification, and the results of the Lymphoma Classification Project (Table 51.2), it is possible to obtain some sort of perspective. Thus, in North America and Europe, B-cell lymphomas account for approximately 85% of all lymphomas. The Lymphoma Classification Project found that, together, large B-cell lymphoma (30.6%), follicular lymphoma (22.1%), mucosa-associated lymphoid tissue (MALT) lymphoma (7.6%), lymphocytic lym-phoma/chronic lymphocytic leukemia (6.7%), and mantle cell lymphoma (6.0%) comprised 73% of all lymphomas. Given that Asian and African patients were represented by only two of the eight centers, these relative incidence figures are less valid for Asia or Africa where overall there is a much lower frequency of follicular lymphoma and, in parts of Asia, a higher frequency of T-cell lymphoma.

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