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A Useful Marker to Distinguish Florid Follicular Hyperplasia From Follicular Lymphoma by Flow Cytometry

Xinjian Chen MD, PhD, Peter E. Jensen MD, Shiyong Li MD, PhD
DOI: http://dx.doi.org/10.1309/WP6H6UD4DXMRQ86T 842-851 First published online: 1 June 2003


HLA-DO expression is regulated during B-cell development and activation. To determine whether the level of HLA-DO expression is a helpful marker in the differential diagnosis between florid follicular hyperplasia and follicular lymphoma, we analyzed single-cell suspensions from 29 lymph node specimens by 4-color flow cytometry. Of the 29 specimens, 7 were from patients with florid follicular hyperplasia, in which the clonality of the germinal center B cells (GCBCs) was indeterminate by flow cytometric immunophenotyping. The remaining 22 cases were follicular lymphomas; neoplastic cells in 2 of these cases lacked expression of surface immunoglobulin light chains. The level of HLA-DO expression in the reactive CD10+ GCBCs in florid follicular hyperplasia was markedly down-regulated compared with the CD10– polytypic B cells of the same specimens. In contrast, the level of HLA-DO expression in the CD10+ neoplastic cells in all cases of follicular lymphomas was similar to that of the CD10– polytypic B cells, thus higher than the reactive CD10+ GCBCs. This difference was confirmed by immunohistochemical staining. Our results suggest that HLA-DO is a useful marker to differentiate florid follicular hyperplasia from follicular lymphoma by flow cytometry, particularly when clonality of the CD10+ B cells is in question.

Key Words:
  • HLA-DO
  • Florid follicular hyperplasia
  • Germinal center B cells
  • Follicular lymphoma
  • Flow cytometry