title: Cytogenetic aberrations and immunoglobulin VH gene mutations in clinically benign CD5- monoclonal B-cell lymphocytosis.
abstract: The finding of monoclonal B-cell lymphocytosis (MBL) raises questions on the nature of clonal cell expansion and its risk of progression. We identified and characterized 7 cases of clinically benign clonal B-cell lymphocytosis. The clonal lymphocytes were clearly of CD5- and non-chronic lymphocytic leukemia (CLL) phenotype. All cases had mild to moderate absolute lymphocytosis. The clonal population accounted for 95% to 99% of B cells. For a follow-up period of 4 to 16 years, clonal lymphocytosis was persistent but virtually not progressing. Patients' conditions remained clinically stable and asymptomatic. The clonal populations had somatic hypermutations of the VH gene in 6 cases, indicating a germinal center or post-germinal center B-lymphocyte origin. Clonal cytogenetic aberrations were found in 5 of 6 cases, with 2 clones bearing isochromosome 17q that resulted in loss of p53 and 2 other clones with 7q abnormalities. By the presence of absolute lymphocytosis, this series differs from MBL cases identified by sensitive flow cytometry in normal populations. The phenotypic profiles are distinct from that of benign CLL. We suggest these CD5-B-cell lymphocytosis cases may represent an intermediate condition between covert clonal expansions and overt malignancy.
authors.affiliation: Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Canada.
authors.forename: Dominick
authors.initials: D
authors.lastname: Amato
authors.forename: David G
authors.initials: DG
authors.lastname: Oscier
authors.forename: Zadie
authors.initials: Z
authors.lastname: Davis
authors.forename: Sarah
authors.initials: S
authors.lastname: Mould
authors.forename: Jianing
authors.initials: J
authors.lastname: Zheng
authors.forename: Elena
authors.initials: E
authors.lastname: Kolomietz
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000473:pathology*; D018956:CD5 Antigens / Q000032:analysis*; D002869:Chromosome Aberrations; D005260:Female; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics; D008218:Lymphocytosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation
chemical_list: D018956:CD5 Antigens; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region