High incidence of leukemic phase in follicular lymphoma in Akita, Japan: clinicopathologic, immunological and cytogenetic studies.

A leukemic phase occurred in 7 of 11 (64%) Japanese patients with follicular lymphoma. The clinical and hematologic features at the onset of this phase were splenomegaly, anemia, and thrombocytopenia. The lymphoma cells expressed monoclonal surface immunoglobulins with moderate to strong intensity in all 7 of the patients diagnosed as leukemic. Various B-cell associated antigens were expressed as follows: CD19 (5/6), CD20 (7/7), and CD10 (6/7). The reactivity to these markers was comparable in the lymph node and blood samples. The expression of CD38 antigen was much lower in the lymphoma cells of the blood than in those of the lymph nodes. Cytogenetic studies of the lymph nodes of follicular lymphoma in leukemic phase revealed a common chromosomal aberration, of t(14;18)(q32;q21) and +18, in 2 patients successfully analyzed. Although the follicular lymphomas in the leukemic phase in these patients in Akita, Japan, were consistent with those in the West with respect to morphology, immunology and cytogenetics, the high incidence of leukemic manifestations may be a salient feature of Japanese cases.