Prevalence and Relative Proportions of CLL and non-CLL Monoclonal B-cell Lymphocytosis Phenotypes in the Middle Eastern Population

• Published in: Hematology/oncology and stem cell therapy 2017-03, Vol.10 (1), p.42-43
• Main Authors: Aljurf, Mahmoud, Rawas, Faisal, Alnounou, Randa, Bakshi, Nasir, Chaudhri, Naeem, Khalil, Salem, Almohareb, Fahad, Albitar, Maher
• Format: Article
• Language: English
• Subjects: B-Lymphocytes; Chronic Lymphocytic Leukemia; Female; Hematology, Oncology and Palliative Medicine; Humans; Leukemia, Lymphocytic, Chronic, B-Cell - epidemiology; Lymphocytosis - epidemiology; Male; Middle Aged; Middle East; Monoclonal B-Cell Lymphocytosis; Prevalence
• ISSN: 1658-3876
• DOI: 10.1016/j.hemonc.2016.09.003

Abstract Chronic lymphocytic leukemia (CLL) is considered more common in Western countries and its incidence is believed to decrease moving east across the globe .Therefore, the prevalence of monoclonal B-cell lymphocytosis (MBL), a pre-CLL condition, is also expected to be less common in non-Western countries. Monoclonal B-cell lymphocytosis1 is characterized by the presence of less than 5000 x 109/L circulating clonal B-cells that can be CD5+ or CD5-.In Western countries, MBL prevalence as detected by flow cytometry varies from 0.6% to 14% in healthy individuals older than 40 years, dependent on the level of sensitivity and number of parameters applied. Using 4 to 6 color flow cytometry, most studies report a prevalence of approximately 5% in the Western population with the CLL-phenotype about 5 times more prevalent than the non-CLL phenotype. It is important to distinguish this entity from overt CLL as the elderly population expands and flow cytometric immunophenotyping increasingly provides a very high level of detection. More individuals are incidentally found to have MBL2. Review of the current literature indicate that while most cases of CLL are preceded by MBL, only 1-2% may progress to CLL requiring therapy3. The epidemiologic and genetic factors associated with MBL contributing to progression to CLL are not properly identified. MBL also carries identical frequency of cytogenetic abnormalities observed in CLL but it has yet to be defined if any subgroup will predict progression to CLL3,4. MBL has been classified as MBL with CLL-like phenotype, MBL with atypical CLL phenotype and MBL with non-CLL phenotype 5. MBL incidence and relative proportions of CLLphenotype versus non-CLL phenotype have not been adequately studied in non-Western countries. We investigated the prevalence and phenotype of MBL in a population sample in the Middle East.