What does it mean I have a monoclonal B-cell lymphocytosis?: Recent insights and new challenges

• Published in: Seminars in oncology Vol. 43; no. 2; pp. 201 - 208
• Main Authors: Scarfò, Lydia, Ghia, Paolo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2016
• Subjects: B-Lymphocytes - metabolism; B-Lymphocytes - pathology; Cellular Microenvironment; Chronic lymphocytic leukemia; Clonal Evolution - genetics; Cytogenetic; Cytogenetic Analysis; Diagnosis, Differential; Disease Management; Hematology, Oncology and Palliative Medicine; High-Throughput Nucleotide Sequencing; Humans; Immunoglobulin genes; Immunoglobulin Heavy Chains - genetics; Immunophenotyping; Leukemia, Lymphocytic, Chronic, B-Cell - diagnosis; Leukemia, Lymphocytic, Chronic, B-Cell - genetics; Leukemia, Lymphocytic, Chronic, B-Cell - metabolism; Leukemia, Lymphocytic, Chronic, B-Cell - therapy; Lymphocyte Count; Lymphocytosis - diagnosis; Lymphocytosis - genetics; Lymphocytosis - metabolism; Lymphocytosis - therapy; Monoclonal B-cell lymphocytosis; Next-generation sequencing; Immunoglobulin genes; Chronic lymphocytic leukemia; Next-generation sequencing; Monoclonal B-cell lymphocytosis; Cytogenetic
• ISSN: 0093-7754; 1532-8708
• DOI: 10.1053/j.seminoncol.2016.02.013

Monoclonal B-cell lymphocytosis (MBL) is defined as a laboratory abnormality where small (<5 x 109/L) clonal B-cell populations are detected in the peripheral blood of otherwise healthy subjects. According to the immunophenotype, MBL is labeled as chronic lymphocytic leukemia (CLL)-like (75% of cases), atypical CLL, and CD5-negative. Concentration of clonal B cells differentiates low- (LC) and high-count (HC)-MBL (< or ≥ 0.5 x 109/L, respectively). Thanks to technical improvements, we are able to identify CLL-like clonal B-cell populations at increased frequency with age, but we are still far from understanding its relationship with clinically overt CLL. LC-MBL, requiring high-throughput screening technique to be identified in population studies, seems to be a bird of a different feather and several hints suggest that LC-MBL is related to aging and/or chronic antigenic stimulation. Immunogenetic, cytogenetic and genetic data support the notion that HC-MBL, usually identified in the clinical setting, is a premalignant condition and, based on biological parameters, it is frequently difficult to differentiate it from early stage CLL. The rapid improvement and widespread availability of cutting-edge technology, in particular next-generation sequencing (NGS), raises hope that we are getting closer to unveiling the fundamental nature of MBL and CLL and how they are related to each other.