Monoclonal B cell lymphocytosis: Clinical and population perspectivesHow to cite this article: Caporaso NE, Marti GE, Landgren O, Azzato E, Weinberg JB, Goldin L and ShanafeltT.Monoclonal B Cell lymphocytosis: clinical and population perspectives. Cytometry Part B 2010; 78B Suppl. 1: S115–S119.

Monoclonal B Cell Lymphocytosis MBL refers to clones of CLLlike cells that exhibit CLL characteristics that fall short of the numbers required for CLL diagnosis. Data from large CLL kindreds document increased prevalence of MBL suggesting a genetic contribution to its etiology. The molecular features that favor progression of MBL to CLL are poorly understood but an elevated Bcell count is a risk factor for progression. An important consideration when evaluating volunteers from CLL families who are willing to donate bone marrow is that MBL be ruled out since the MBL donor clone could result in a second CLL in the recipient. Further studies of MBL are needed to identify the molecular features and how they evolve during progression. Published 2010 WileyLiss, Inc.