Monoclonal B lymphocytosis (MBL) has been recognized as a novel diagnostic condition. This study aims at the identification of clonal lymphocytosis in the patients with asymptomatic lymphocytosis. A total of 203 patients were evaluated for clonal B and T lymphocytosis by using flow cytometry and multiplex-PCR. Among them clonal B- or T-cells were detected in 54.2% of the cases, of which 38.4% were clonal B-cells and 15.8% were clonal T-cells cases. By immunophenotype, MBL was classified into the chronic lymphocytic leukemia (CLL) type (21.7%) and non-CLL-type (7.4%). Flow cytometry analysis and cell counts were used to determine the size of clonal population, and the data indicate that MBL and CLL are present in a continuous spectrum of clonal expansion. The findings may contribute to the current understanding of MBL and evaluation of incidental lymphocytosis. Further studies are required to evaluate clonal progression as a precursor stage of lymphoid malignancy.

Monoclonal B lymphocytosis (MBL) has been recognized as a novel diagnostic condition. This study aims at the identification of clonal lymphocytosis in the patients with asymptomatic lymphocytosis. A total of 203 patients were evaluated for clonal B and T lymphocytosis by using flow cytometry and multiplex-PCR. Among them clonal B- or T-cells were detected in 54.2% of the cases, of which 38.4% were clonal B-cells and 15.8% were clonal T-cells cases. By immunophenotype, MBL was classified into the chronic lymphocytic leukemia (CLL) type (21.7%) and non-CLL-type (7.4%). Flow cytometry analysis and cell counts were used to determine the size of clonal population, and the data indicate that MBL and CLL are present in a continuous spectrum of clonal expansion. The findings may contribute to the current understanding of MBL and evaluation of incidental lymphocytosis. Further studies are required to evaluate clonal progression as a precursor stage of lymphoid malignancy.