2002 Volume 42 Issue 2 Pages 47-54
The incidence and preferential sites of malignant lymphomas were retrospectively investigated by reviewing archived pathological files (1985 to 1996) in 11 major hospitals in Yamagata Prefecture, a HTLV-1-nonendemic area of Japan. In addition, re-evaluation of 212 recent cases based upon the newly-published WHO classification was performed. The following results were obtained: 1) the actual number of lymphoma patients was increasing annually, 2) the incidence rate of extranodal lymphomas was 61.3%, with the gastro-intestinal tract and Waldeyer's ring being the major preferential sites, 3) the incidence of extranodal lymphomas seemed to be increasing annually, whereas that of nodal lymphomas was not, 4) B-cell lymphomas were dominant (69.8%), in a percentage similar to that of a previous nationwide investigation, 5) major categories among the B-cell lymphomas were diffuse large B-cell lymphoma, follicular lymphoma and extranodal B-cell lymphoma of MALT, 6) the percentage of T-cell lymphomas was less than that of the nationwide investigation, 7) angioimmunoblastic T-cell lymphoma was a major subtype of T-cell lymphoma, and 8) the incidence rate of Hodgkin lymphoma was 5.7% of total malignant lymphomas.