MORPHOLOGICAL AND IMMUNOPHENOTYPICAL CHARACTERIZATION OF JAPANESE B-CELL LYMPHOCYTIC-LEUKEMIA

We have analyzed the clinical and laboratory features of 42 patients w ith B-cell leukemia. Based on the FAB criteria, the cases were classif ied in 3 groups: I) typical CLL 15, II) atypical CLL 9 which included 6 cases with large cells, and III) B-cell lymphoma in leukemic phase 1 8. Cases diagnosed as typical CLL (group I) had similar features to th ose seen in CLL patients from Western countries. The morphology and ma rkers in cases from group III corresponded to B-cell lymphoma in leuke mic phase. On the other hand, group II included 3 cases classified as atypical CLL according to FAB criteria. 1 CLL/PL and 2 mixed CLL and 6 cases with lather distinct features, namely: 1) lymphocytosis (42 a 4 1 x 10(9)/1 in average) with large mature-looking lymphocytes with abu ndant cytoplasm: 2) an immunological profile consistent with CLL but, in addition with the consistent expression of CD38; 3) absence of a mo noclonal band in the serum and 4) a clinical course and prognosis simi lar to CLL. Our findings suggest the existence of a B-cell disorder in Japan very close to CLL but distinct from typical and atypical CLL as seen in Western countries. Further studies would clarify whether such an entity is exclusively confined to Japan having a distinct natural history.