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[Chronic lymphocytic leukemia in Japan]
1Second Department of Internal Medicine, Faculty of Medicine, Mie University.
Insights
Japanese B-cell chronic lymphocytic leukemia (CLL) patients exhibit distinct phenotypic characteristics, including high expression of activated antigens. The incidence of CLL and its subtypes is significantly lower in Japan compared to Western countries.
Area of Science:
- Hematology
- Oncology
- Immunology
Context:
- Evaluation of 41 patients diagnosed with B-cell chronic lymphocytic leukemia (CLL) in Japan.
- Classification into five groups (CLL, CLL-L, CLL/PL, PLL, LSCL) based on morphological criteria.
- Comparison of CLL characteristics between Japanese and Western populations.
Purpose:
- To classify Japanese CLL patients based on morphological criteria.
- To investigate the phenotypic characteristics of CLL in Japan.
- To compare the incidence and characteristics of CLL in Japan with Western countries.
Summary:
- Seven out of 41 patients (17%) had typical CLL (>90% small lymphocytes).
- Japanese CLL cases showed high expression of activated antigens (CD22, PCA1, CD25), suggesting a higher proportion of atypical CLL.
- Molecular analysis revealed C mu gene deletion in three sIg-negative cases. The incidence of CLL subtypes in Japan is approximately 1/10 of that in Western countries.
Impact:
- Highlights unique phenotypic features of CLL in the Japanese population.
- Suggests potential differences in CLL pathogenesis or presentation between ethnic groups.
- Provides crucial epidemiological data on CLL incidence in Japan.
Abstract:
Forty-one patients diagnosed as having B-cell chronic lymphocytic leukemia in Japan were evaluated. Patients were classified into five groups (CLL, CLL-L, CLL/PL, PLL, LSCL) according to differential counts of small lymphocytes, large lymphocytes, prolymphocytes, immunoblasts and/or lymphosarcoma cells among the lymphoid cells in the first available peripheral smears based on Melo's morphological criteria. Patients with typical CLL, defined as having more than 90% small lymphocytes, were seven (17%) of 41 patients. Phenotypical characteristic of CLL and its subgroups in Japan was considered to be the high expression of activated antigens, such as CD22, PCA1 and CD25. This finding may support the relatively higher proportion of atypical CLL with high percentage of large lymphocytes or prolymphocytes in Japan than that in Western countries. The molecular biological analysis revealed the deletion of C mu gene in one allele in three sIg-negative cases. The incidence of CLL, CLL-L and CLL/PL in Japan was deduced to be 1/10 of that in Western countries.