Flow Cytometric Assessment of T-cell Chronic Lymphoproliferative Disorders

Flow cytometric immunophenotyping for hematologic neoplasms

“…67,74 In addition, it is important to recognize that NK cells normally demonstrate somewhat variable intensity staining for CD2, CD7, CD16, and CD56. 68,70 Populations of abnormal T and NK cells can also be recognized by expression of antigens that are not normally expressed in these lineages. The myeloid antigens CD15, CD13, and CD33 have been described on some mature T-cell malignancies and may lead to confusion with acute myeloid leukemia.…”

“…T-and NK-cell lymphoid neoplasms often demonstrate altered expression of T cell-and NK cell-associated antigens. 68,70 On occasion, this is reflected in complete lack of staining for one or more pan-T-cell antigens. Indeed, lack of staining for multiple T cell-associated antigens may impart a "null" phenotype and raise questions about the lineage of the cells.…”

“…68,80 Unlike CTCL and ATLL, T-PLL is usually positive for CD7, negative for CD25, and lacks aberrant loss or decreased expression of other T-cell antigens. 68 The cells of T-PLL are usually negative for NK-associated antigens and cytotoxic granule-associated proteins; therefore, expression should lead to consideration of a rare CD4 ϩ LGL. Correlation with morphologic and clinical findings remains important.…”

“…Some of the more frequently encountered abnormalities include brighter or weaker staining of T cells for CD3 or CD5; weaker staining of NK cells for CD2, CD7, CD56, and CD57; and more uniform bright expression by NK cells of CD8 and CD16. 68,70 However, these abnormalities must be distinguished from normal small subsets of T cells that may have a somewhat unusual phenotype, (eg, ␥/␦ ϩ T cells with low intensity or absence of staining for CD5 and possibly CD2 and brighter CD3; CD45RO ϩ primarily memory T cells with brighter CD2 staining than CD45RO Ϫ primarily naive T cells). 67,74 In addition, it is important to recognize that NK cells normally demonstrate somewhat variable intensity staining for CD2, CD7, CD16, and CD56.…”

“…67,68 Table 3 outlines the normal pattern of staining and clinical utility of reagents recommended by the 2006 Bethesda consensus group for the evaluation of the T-cell lineage. However, neoplastic T-and NK cells are often more difficult to identify than neoplastic B cells.…”