Determination of immunophenotypic aberrancies provides better assessment of peripheral blood involvement by mycosis fungoides/Sézary syndrome than quantification of CD26- or CD7- CD4+ T-cells.

Blood involvement by mycosis fungoides (MF)/Sézary syndrome (SS) influences prognosis and therapeutic decisions. MF/SS blood stage is currently determined by absolute CD4 + CD26- or CD4 + CD7-cell counts, which quantification method may overestimate MF/SS by including CD26- or CD7- normal CD4+ T-cells, or underestimate disease burden when MF/SS cells show incomplete loss of CD26 and/or CD7. Recently, through the standardization effort led by the International Clinical Cytometry Society (ICCS), recommendation was made to quantify MF/SS by enumerating immunophenotypically aberrant CD4+ T-cells, rather than CD26- or CD7- in isolation. We compared these two quantitation methods in 309 MF/SS patients who had blood samples analyzed by flow cytometry immunophenotyping (FCI) over a 1-year period. Using the European Organization of Research and Treatment of Cancer (EORTC)/International Society for Cutaneous Lymphomas (ISCL) criteria, 221 (71.5%) patients had a blood stage corresponding to B0, 57 (18.4%) to B1, and 31 (10%) to B2. By FCI analysis, a total of 62 patients (20.0%) were found positive for MF/SS. Among EORTC B0 patients, 11/221 (5%) were positive by FCI (false negatives), and among EORTC Stage B1 patients, 35/57 (61%) were negative by FCI (false positives). Regarding patients positive for MF/SS cells by FCI, there was an overall excellent correlation (r = .999, p < .001) between the EORTC/ISCL method and FCI method; however, four (6.5%) patients would have an altered B stage between B0 and B1. The MF/SS cell quantification method using immunophenotypic aberrancies, as recommended by the ICCS, allows to distinguish MF/SS cells from background benign T-cells and enables for more accurate staging, especially among patients currently being considered to have B0 and B1 stage diseases.

Lyapichev KA ，Bah I ，Huen A ，Duvic M ，Routbort MJ ，Wang W ，Jorgensen JL ，Medeiros LJ ，Vega F ，Craig FE ，Wang SA ... -  《-》

The relevance of the CD4+ CD26- subset in the identification of circulating Sézary cells.

Bernengo MG ，Novelli M ，Quaglino P ，Lisa F ，De Matteis A ，Savoia P ，Cappello N ，Fierro MT ... -  《BRITISH JOURNAL OF DERMATOLOGY》

Blood classification and blood response criteria in mycosis fungoides and Sézary syndrome using flow cytometry: recommendations from the EORTC cutaneous lymphoma task force.

Our current mycosis fungoides (MF) and Sézary Syndrome (SS) staging system includes blood-classification from B0-B2 for patch/plaque/tumour or erythroderma based on manual Sézary counts but results from our EORTC survey confirm these are rarely performed in patch/plaque/tumour MF, and there is a trend towards using flow cytometry to measure blood-class. Accurately assigning blood-class effects overall stage and the 'global response' used to measure treatment responses in MF/SS and hence impacts management. The EORTC Cutaneous Lymphoma Task Force Committee have reviewed the literature and held a Workshop (June 2017) to agree a definition of blood-class according to flow cytometry. No large study comparing blood-class as defined by Sézary count with flow cytometry has been performed in MF/SS. The definition of blood-class by flow cytometry varies between publications. Low-level blood involvement occurs in patch/plaque/tumour much less than erythroderma (p < 0.001). The prognostic relevance of blood involvement (B1 or B2) in patch/plaque/tumour is not known. Studies have not shown a statistically worse difference in prognosis in erythrodermic MF patients with low-level blood involvement (IIIB) versus those without (IIIA), but Sezary patients who by definition have a leukaemic blood picture (staged IVA1 or higher) have a worse prognosis. For consistency flow, definition for blood-class must be an objective measurement. We propose absolute counts of either CD4+CD7-or CD4+CD26-where B0<250/μL, B1 = 250/μl-<1000/μL and B2≥1000/μL plus a T-cell blood clone. Fluctuations between B0 and B1 should not be considered in the treatment response criteria until further prognostic information is known.

Scarisbrick JJ ，Hodak E ，Bagot M ，Stranzenbach R ，Stadler R ，Ortiz-Romero PL ，Papadavid E ，Evison F ，Knobler R ，Quaglino P ，Vermeer MH ... -  《-》

Revisiting the initial diagnosis and blood staging of mycosis fungoides and Sézary syndrome with the KIR3DL2 marker.

The early diagnosis of Sézary syndrome (SS) is challenging. Loss of CD7 and CD26 expression on CD4+ T cells is the currently used criterion in the initial diagnosis and staging of patients with SS. Our aim was to evaluate the respective value of CD26, CD7 and KIR3DL2 expression on CD4+ T cells and total lymphocytes at initial diagnosis of SS. This prospective study included 254 patients with clinical features consistent with cutaneous T-cell lymphoma seen at our institution between March 2014 and February 2019. Peripheral blood analysis by flow cytometry was performed for each patient at the time of diagnosis and during follow-up. The diagnosis of SS was based on ISCL/EORTC criteria. The presence of KIR3DL2+ Sézary cells (SCs) ≥ 200 μL-1 correlated with the diagnosis of SS, with sensitivity of 88·6% and specificity of 96·3%. All 154 patients with either inflammatory skin disease or other haematological disease had KIR3DL2+ cells < 200 μL-1 , while eight of them had CD4+ CD26- T cells ≥ 1000 μL-1 . Of five patients with SS and lymphopenia, four had CD4+ CD7- T cells < 1000 μL-1 and three had CD4+ CD26- T cells < 1000 μL-1 . However, all of them had KIR3DL2+ CD4+ T cells ≥ 200 μL-1 . Among patients with available samples during evolution, all B1-staged patients with ≥ 200 μL-1 KIR3DL2+ SCs at diagnosis evolved to B2 stage within 7 months. KIR3DL2 expression on T cells is highly specific and helps the early diagnosis of SS, especially in those patients with lymphopenia. What's already known about this topic? In the ISCL/EORTC cutaneous T-cell lymphoma (CTCL) categorization of blood involvement (B0-B2), B2 is defined as a T-cell receptor clonal rearrangement in blood, associated with high blood-smear Sézary cell (SC) count. Flow cytometry was developed to circumvent interobserver variability of SC manual counts; however, it mostly relies on detection of cells lacking CD7 and/or CD26 expression. We previously reported the reliability of KIR3DL2 as the first positive SC marker. What does this study add? Based on our analysis of 254 patients, we propose that KIR3DL2 be added to the ISCL/EORTC criteria for initial diagnosis of Sézary syndrome (SS) and B2 staging. This marker improved sensitivity of SS B2-stage CTCL diagnosis with a specificity > 95%, especially for patients with lymphopenia. We found KIR3DL2 helped early diagnosis of SS and was more reliable than CD26 in assessing blood tumour burden during therapy. What is the translational message? SC quantification is the major means of staging at initial diagnosis and monitoring blood tumour burden in a clinical trials setting. We recommend using a threshold value of KIR3DL2+ SCs ≥ 200 μL-1 or KIR3DL2+ SCs/lymphocytes ≥ 10% in the diagnostic criteria of SS and propose a novel algorithm for CTCL B2 blood staging.

Roelens M ，de Masson A ，Ram-Wolff C ，Maki G ，Cayuela JM ，Marie-Cardine A ，Bensussan A ，Toubert A ，Bagot M ，Moins-Teisserenc H ... -  《-》

Flow cytometric detection of peripheral blood involvement by mycosis fungoides and Sézary syndrome using T-cell receptor Vbeta chain antibodies and its application in blood staging.

Feng B ，Jorgensen JL ，Jones D ，Chen SS ，Hu Y ，Medeiros LJ ，Wang SA ... -  《-》