Trisomy 8 demonstrated in a case of CLL
Aim: A rare cytogenetic finding was demonstrated in a case of chronic lymphocytic leukemia (CLL).
Methods:
1. Flow cytometry was done on bone marrow and blood specimen.
2. Cytogenetic analysis was carried out on bone marrow and lymphoid cells from peripheral blood using standard G-banding technique.
Results: Bone marrow flow cytometry done 4 year ago expressed CD19,CD20, CD5,CD23 and SMIG with clonality in the kappa chain. CD5 and CD19 co-expression was demonstrated. A diagnosis of chronic lymphocytic leukemia was made. Cytogenetic analysis carried out on overnight and direct cultures that were set up without stimulation showed a normal karyotype. The patient was recently readmitted,flow cytometry on blood detected 26% of clonal B cells. They expressed CD5 and CD19 and weak CD23+ with kappa chain restriction. CD79b and FMC-7 were both negative. This was consistent with the continued presence of circulation clonal B-lymphocytes. Cytogenetic analysis done on peripheral blood stimulated with B cell mitogen demonstrated two cells with trisomy 8.Fluorescence in-situ hybridization (FISH) using an LSI CEP 8 probe performed on the archival bone marrow specimen showed three hybridization signals in 40% of 200 interphase cells scored.This confirmed that the trisomy 8 abnormality was present in both the blood and bone marrow samples.
Conclusion: The most frequent abnormality in B-CLL, found in one third of the abnormal cases, is trisomy 12. Deletion of 13q14, is the most frequent structural aberration found in B-CLL, followed by 14q32 band rearrangements. Less frequently, alterations of chromosomes 11, 6, 18, 3, 17 and 8 were observed. Trisomy 8 is the most frequent isolated abnormality found in acute myeloid leukemia and myelodysplastic syndrome. But trisomy 8 as the sole abnormality in CLL is very rare. The significance of trisomy 8 in CLL remains to be seen.