Long‐term follow‐up of monoclonal B‐cell lymphocytosis detected in environmental health studies

Abstract

Background: Four individuals in whom Monoclonal B cell Lymphocytosis (MBL) had been previously detected were evaluated for the fourth time after 15-18 years since initial testing. All four were environmental health study participants without hematologic malignancies who had elevated absolute B cell counts at initial testing.Methods: The current laboratory evaluation included complete blood counts, lymphocyte immunophenotypes, immunoglobulin heavy-chain variable (IGHV) gene mutation status, and serum tests for monoclonal immunoglobulins and free light chains. Results from this evaluation were compared with those from the three previous evaluations. Clinical status was assessed by reviewing medical records.Results Conclusions: A diversity of clonal evolution was observed in these MBL cases. These observations suggest that long-term follow-up studies using standardized MBL subcategories are essential to understanding B-cell pathobiology and optimizing clinical management. Published

Monoclonal B-cell lymphocytosis is characterized by mutations in CLL putative driver genes and clonal heterogeneity many years before disease progression

“…1,9,10 In addition, previous reports have demonstrated the co-existence of two B-cell subclones in a small subset of MBL cases, 11 and clonal changes in sequential MBL samples measured by IGHV mutational analysis. 12 …”

Detection of 13q deletion in patients with chronic lymphocytic leukemia and its correlation to hematopathological parameters

“…However, we and others did not find significant differences in the baseline characteristics and clinical outcome among CLL patients with monoallelic or biallelic 13q deletions (66)(67)(68)(69) . It is worth noting that 13q14 region can be inactivated by other mechanisms such as copy neutral loss of heterozygosity and epigenetic silencing by DNA methylation of CpG islands or histone deacetylation (70,71) . Thus, it is feasible to assume that the potential effect of the biallelic 13q losses on the prognosis could be masked either by the size of the deleted region or the inactivation of the remaining allele by other mechanisms (65).…”

Smoldering mantle cell lymphoma

“…With the advent of flow cytometry, monoclonal lymphocytes can be found in up to 3.5~12% of healthy population aged over 40 years old [ 82 – 88 ]. “Monoclonal B-lymphocytosis” (MBL) is defined as the count of B-lymphocytes in the peripheral blood less than 5000/ul [ 89 ], with lack lymph node or organ enlargement, cytopenias, or disease-related symptoms [ 90 ].…”