[Phenotypical diagnosis of Japanese chronic lymphocytic leukemia--an international cooperative study based on the French-American-British classification of mature B-cell leukemias].

To better understand the accuracy in the diagnosis of chronic lymphocytic leukemia (CLL) and characterize the clinical features of CLL in Japan, where the disease is extremely rare, an international cooperative study was conducted by hematologists between Japan and UK. Blood and bone marrow films from 36 patients with a possible-diagnosis of CLL were referred to two laboratories of Nagasaki University Hospital (Nagasaki) and Royal Marsden Hospital (London). According to the FAB criteria, typical CLL 16 and CLL/PL 2, a subtype of atypical CLL, were completely accordant in diagnosis. However, phenotypical diagnosis of CLL mixed, the other of atypical CLL, and intermediate lymphocytic leukemia (ILL) in leukemic phase often gave inconsistent results. Especially, 8 cases of atypical CLL designated as likely CLL were equivocal between CLL and ILL, suggesting clinical feature more close to typical CLL than ILL. This indicates the presence of a relatively high incidence of atypical CLL in Japan which dose not exactly fit with the FAB Criteria. Finally, we would like to emphasize that an international cooperative study allows improvement of accuracy in diagnosis and better understanding of the disease entity of lymphoid malignancies, having on ethnically different morbidity.

Trisomy 12 in chronic lymphocytic leukemia detected by fluorescence in situ hybridization: analysis by stage, immunophenotype, and morphology.

Fluorescence in situ hybridization (FISH) with a chromosome 12 specific alpha-centromeric probe was performed on interphase cells from 183 patients with B-cell chronic lymphocytic leukemia (CLL). Twenty one cases with trisomy 12 (11.5%) were detected. The number of trisomic cells ranged from 5.5% to 76% (mean 38.5%). No correlation was found between the presence of trisomy 12 and white blood cell count, hemoglobin level, platelet count, a specific immunophenotype, clinical stage, sex, splenomegaly, or lymphadenopathy. Morphologic review of all cases with trisomy 12 showed seven (33%) with more than 10% prolymphocytes and three (14%) with CLL of mixed cell type. While trisomy 12 is the most common chromosomal abnormality in CLL, it is more frequent in morphologically atypical cases, some of which may be undergoing transformation. There was a statistically significant difference in the incidence of atypical cases between those with (47%) and without (7.6%) trisomy 12 (P < .001). It remains to be determined whether this abnormality is associated with a worse prognosis; this is currently being investigated in the context of a national therapeutic trial. The technique used is more sensitive than conventional cytogenetic analysis, which in this series failed to detect trisomy 12 in six cases. FISH allows the systematic study on a large number of patients without the need of metaphase preparations.