Abstract
Background
Peripheral T-cell lymphomas (PTCLs) are heterogenous, mature T-cell neoplasms that are a diagnostic challenge, requiring a combination of morphologic assessment and ancillary studies. Flow cytometry (FC) is a tool used routinely in lymphoma diagnosis; however, most analyses are limited to B-cell evaluation and pathologists generally lack experience evaluating for PTCL. We aimed to describe the immunophenotypic aberrancies observed by FC in PTCL.
Design
PTCLs with FC were collected, excluding primary leukemic processes. Four- and eight-color FC data were reanalyzed with the following antigens (when available): CD2, CD3, CD4, CD5, CD7, CD8, CD30, CD45, CD45RO, CD56, and CD57. Lymphoma cells were compared to normal T cells and an isotype control. Antigen expression was defined as >20%.
Results
Thirty-eight cases were analyzed (29 males, 9 females, 6-86 years, median 62 years), including 29 PTCLs NOS, 4 angioimmunoblastic T-cell lymphomas (AITLs), 3 anaplastic large cell lymphomas, 1 δγ-TCL, and 1 hepatosplenic TCL from 15 bone marrows, 14 lymph nodes, 6 bloods, 2 fluids, and 1 skin. Twenty cases were CD4+, 4 were CD8+, 3 were dual +, and 10 were dual –. Thirty-seven cases (97%) showed global aberrant antigen patterns, median 4 aberrancies/case (1-8). Lymphoma cells accounted for 0.07% to 68% (median 2.6%) of total events. Aberrant CD7 expression was present in 34 of 38 (89%) and was underexpressed in 22 of 34 (65%). CD3 and CD5 were aberrant in 79% of cases each, with two-thirds showing underexpression. CD2 and CD45RO were aberrant in two-thirds of PTCLs, with overexpression in 61% and 92% of those cases, respectively. One AITL showed no aberrancies.
Conclusions
Nearly all PTCLs show immunophenotypic aberrancy compared to normal T cells. Most commonly, PTCL showed aberrant underexpression of CD7, CD3, and CD5 and overexpression of CD2 and CD45RO. Our data support FC panels with CD2, CD3, CD4, CD5, CD7, CD8, and CD45RO to optimize recovery of aberrant T cells.
Immunophenotypic shift of CD4 and CD8 antigen expression in primary cutaneous T-cell lymphomas: a clinicopathologic study of three cases
