title: Quantitative flow cytometric identification of aberrant T cell clusters in erythrodermic cutaneous T cell lymphoma. Implications for staging and prognosis.
abstract: OBJECTIVE
  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.
authors: Department of Hematopathology and Labororatory Medicine, H. Lee Moffitt Cancer Center, , Tampa, Florida, USA.
authors: Pedro
authors: P
authors: Horna
authors: Darcie M
authors: DM
authors: Deaver
authors: Dahui
authors: D
authors: Qin
authors: Lynn C
authors: LC
authors: Moscinski
authors: Eduardo M
authors: EM
authors: Sotomayor
authors: L Frank
authors: LF
authors: Glass
authors: Lubomir
authors: L
authors: Sokol
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping / Q000379:methods*; D053208:Kaplan-Meier Estimate; D018655:Lymphocyte Count; D016410:Lymphoma, T-Cell, Cutaneous / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012751:Sezary Syndrome / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D012878:Skin Neoplasms / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor
keywords: Flow Cytometry; Lymphoma; SkiN