PT  - JOURNAL ARTICLE
AU  - Horna, Pedro
AU  - Deaver, Darcie M
AU  - Qin, Dahui
AU  - Moscinski, Lynn C
AU  - Sotomayor, Eduardo M
AU  - Glass, L Frank
AU  - Sokol, Lubomir
TI  - Quantitative flow cytometric identification of aberrant T cell clusters in erythrodermic cutaneous T cell lymphoma. Implications for staging and prognosis
AID  - 10.1136/jclinpath-2013-201748
DP  - 2014 May 01
TA  - Journal of Clinical Pathology
PG  - 431--436
VI  - 67
IP  - 5
4099  - http://jcp.bmj.com/content/67/5/431.short
4100  - http://jcp.bmj.com/content/67/5/431.full
SO  - J Clin Pathol2014 May 01; 67
AB  - Aims Assessment of peripheral blood tumour burden for staging of cutaneous T cells lymphoma is most often accomplished by flow cytometry (FC) using various non-standarised strategies. We report the results of calculating absolute Sezary cell counts (SCCs) by FC, based on the identification of aberrant T cell clusters on a virtual 6-dimensional space and independently of the expected immunophenotype (6D-FC SCC). Methods 6D-FC SCCs were calculated on 65 peripheral blood specimens from 28 patients with erythrodermic cutaneous T cells lymphoma (stage III or IV). Comparisons were made with recommended FC strategies and correlations with overall mortality were studied. Results At first visit, 17 of 28 patients (61%) had 6D-FC SCCs meeting current criteria for Stage IV disease (≥1000 SC/μL); while only 2 patients (7%) met Stage IV criteria on other tissues. As defined by comprehensive staging using clinicomorphological criteria and 6D-FC SCCs, Stage IV disease identified a subgroup of patients with worse overall survival (p=0.0227). Residual non-aberrant CD4 T cells were markedly decreased in Stage IV disease (p=0.018). Among 65 specimens, discrepancies were observed between 6D-FC SCCs and usual FC thresholds for Stage IV disease, namely a CD4:CD8 ratio ≥10:1 (9 discrepancies, 14%), and ≥40% aberrant CD4 T cells (4 discrepancies, 6%). Surprisingly, 8 cases (12%) from 6 patients exhibited two distinctively separate clusters of aberrant CD4 T cells with different CD7 and/or CD26 expression. Conclusions Visual 6-dimensional identification of aberrant T cell clusters by FC allows for the calculation of clinically significant SCCs. Simplified gating strategies and relative quantitative values might underestimate the immunophenotypical complexity of Sezary cells.