Quantitative flow cytometric identification of aberrant T cell clusters in erythrodermic cutaneous T cell lymphoma. Implications for staging and prognosis

J Clin Pathol. 2014 May;67(5):431-6. doi: 10.1136/jclinpath-2013-201748. Epub 2013 Dec 6.


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.

Keywords: Flow Cytometry; Lymphoma; SkiN.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / analysis*
  • Female
  • Flow Cytometry*
  • Humans
  • Immunophenotyping / methods*
  • Kaplan-Meier Estimate
  • Lymphocyte Count
  • Lymphoma, T-Cell, Cutaneous / immunology*
  • Lymphoma, T-Cell, Cutaneous / mortality
  • Lymphoma, T-Cell, Cutaneous / pathology
  • Male
  • Middle Aged
  • Neoplasm Staging*
  • Predictive Value of Tests
  • Retrospective Studies
  • Sezary Syndrome / immunology*
  • Sezary Syndrome / mortality
  • Sezary Syndrome / pathology
  • Skin Neoplasms / immunology*
  • Skin Neoplasms / mortality
  • Skin Neoplasms / pathology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology
  • Young Adult


  • Biomarkers, Tumor