OBJECTIVETo investigate the application of flow cytometry in diagnosis of T-cell rich diffuse large B-cell lymphoma.

METHODSHistopathologic features, immunohistochemical findings and flow cytometry results of three cases of T-cell rich diffuse large B-cell lymphoma were reviewed retrospectively.

RESULTSIn CD45-side scatter (SSC) dot plot of the first patient, two different CD45-positive lymphoid cell populations were identified. The bright population consisted of both T and B cells, with a T-cell predominance. The dim population consisted mainly of B cells which showed lambda light chain restriction. In the second patient, CD45-positive cells were subdivided into two groups according to CD45-SSC dot plot. The small population consisted of both T and B cells, with a T-cell predominance. The large population consisted mainly of B cells which showed kappa light chain restriction. In the third patient, CD19-positive cells were subdivided into two groups according to the expression of CD20 in CD19-CD20 dot plot. The CD20-positive population expressed both kappa and lambda light chains, while the CD20-negative population demonstrated kappa light chain restriction.

CONCLUSIONSNeoplastic B cells can be distinguished from reactive lymphoid cells in T-cell rich diffuse large B-cell lymphoma by flow cytometry, according to a number of parameters which include intensity of antigen expression, loss of antigens, expression of non-B-cell lineage antigens, patterns of forward scatter (FSC) and/or SSC, and expression of immature B-cell antigens.