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Characterization of Incidentally Identified Minute Clonal B-Lymphocyte Populations in Peripheral Blood and Bone Marrow

Weina Chen MD, PhD, Sheryl L. Asplund MD, Robert W. McKenna MD, Steven H. Kroft MD
DOI: http://dx.doi.org/10.1309/6UGDU03VVD0L98LQ 588-595 First published online: 1 October 2004


We describe 69 patients in whom small clonal B-cell populations were detected incidentally in blood and bone marrow samples by flow cytometric studies. In 20 patients (29%), non-Hodgkin lymphoma (NHL) subsequently was diagnosed 0 to 40 months (median, 0.1 month) from initial flow cytometric studies. In 49 patients (71%), there was no evidence of NHL after 0.5 to 72 months (median, 16 months). Patients without overt NHL had a higher absolute WBC count than patients with NHL (2,260/μL vs 1,470/μL [2.26 vs 1.47 × 109/L]; P < .01). Otherwise, there were no clinical or hematologic differences between the 2 groups. We identified 70 clonal populations in the 69 patients, ranging from 0.05% to 4.5% (median, 1.28%) of events. The mean percentage of clonal B cells was similar for the 2 groups. The populations were CD5–/CD10– in 34 cases; CD5+, chronic lymphocytic leukemia–like in 19; CD5+, indeterminate in 9; CD10+ in 3; hairy cell leukemia–like in 3; and CD5+, mantle cell lymphoma–like in 2. There were no immunophenotypic differences in patients with and without overt NHL.

Key Words:
  • Flow cytometry
  • Small B-cell lymphoma
  • Incidental
  • Marginal zone
  • Chronic lymphocytic leukemia