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Prominent Clonal B-Cell Populations Identified by Flow Cytometry in Histologically Reactive Lymphoid Proliferations

Steven J. Kussick MD, PhD, Michael Kalnoski MD, Rita M. Braziel MD, Brent L. Wood MD, PhD
DOI: http://dx.doi.org/10.1309/4EJ8T3R2ERKQ61WH 464-472 First published online: 1 April 2004


We describe 6 cases from the University of Washington Hematopathology Laboratory (Seattle) in which prominent, clonal, follicle center B-cell populations were identified by flow cytometry and confirmed by molecular methods, but in which the histologic features showed reactive follicular hyperplasia without evidence of bcl-2 overexpression or the t(14;18). The 6 cases included 5 lymph node biopsy specimens and 1 tonsillectomy specimen. Of the 6 cases, 5 occurred in young males (8–28 years) with no known immunologic abnormality; the other case was a 32-year-old, HIV-positive woman. In all 6 cases, clonal CD10+ B cells representing at least 20% of the total B cells were identified. Available clinical follow-up ranging from 13 to 56 months revealed no evidence of lymphoma in any of the 6 patients. Our findings add rare cases of follicular hyperplasia to the list of histologically reactive settings in which clonal B-cell populations might be present.

Key Words:
  • Flow cytometry
  • Follicular hyperplasia
  • Clonality
  • B cell
  • Polymerase chain reaction
  • PCR