Characterization of Tissue Findings in Bone Marrow with Small Monoclonal B-Cell Populations
Anmaar Abdul-Nabi, LoAnn Peterson, Beverly Nelson. Northwestern University, Chicago, IL
Background: Flow cytometry immunophenotyping (FC) allows detection of small populations of CLL type or CD5- monotypic B-cells (MBCs) in the blood. When MBCs are not associated with overt clinical disease or tissue involvement, and are <5000/uL, the term monoclonal B-lymphocytosis (MBL) is used. Most studies have focused on PB MBL, but low levels of MBCs are also found in BM. In this study, we evaluated BM pathology and clinical setting when small MBC populations similar to MBL were detected in the aspirate by flow cytometry.
Design: BMs performed between 01/1999 and 12/2010 that showed MBCs <5% of total events by 4-8 color flow cytometry were selected for review. In BM biopsies done for lymphoma staging, only small clones with a phenotype different from the original lymphoma were included PB lymphocyte counts were <5000/uL. History and physical findings were retrieved from the EMR. H&E stained BM sections and immunostains (IHC) for CD3, CD20 or PAX5 or CD79a were reviewed.
|Clone Type (no. of cases)||Reason for BM||H&E/ IHC|
|Lymphoma staging||AML||Plasma cell dyscrasia||Cytopenias||lymphoid aggregates (LA)||B-cell rich LA||T-cell rich LA|
|None CLL (13/24)||6||0||4||3||4/13||1||3|