Peripheral blood monocytes include three subsets defined by CD14 and CD16 surface markers. An increase in the CD14++CD16− classical monocyte fraction ≥ 94% of the total monocytes was proposed to rapidly and efficiently distinguish chronic myelomonocytic leukemia from reactive monocytosis. The robustness of this assay required a multicenter validation. The flow cytometry assay designed to quantify peripheral blood monocyte subsets was implemented by multiple diagnosis laboratories in France. A nationwide survey was performed to evaluate its performance. All the 48 French laboratories answered the questionnaire, revealing that 63% use this assay routinely. Central blind reanalysis of 329 cytometry files collected from five laboratories demonstrated an excellent correlation in classical monocyte fraction measurement (r = 0.93; p < 0.0001). The cutoff value of 94% classical monocytes being the critical readout for diagnosis, we then compared 115 patients with classical monocytes ≥ 94% and 214 patients with a fraction < 94% between initial analysis and reanalysis. An agreement was obtained in 311 files. Finally, an overt diagnosis, available for 86 files, confirmed a good sensitivity (93.6%) and specificity (89.7%). This survey demonstrates the robustness of the flow assay with limited variability of classical monocyte percentage between centers, validates the 94% cutoff value, and confirms its sensitivity and specificity.

© F e r r a t a S t o r t i F o u n d a t i o neral T-cell lymphomas (PTCL) but mainly in angioimmunoblastic T-cell lymphoma (AITL). [14][15][16][17][18] PTCLs have also been reported during CD3-CD4 + L-HES course. 6,9,[19][20][21][22][23][24] Two of 23 patients currently followed in the French Eosinophil Network, and one more patient recently reported by others, 25 developed well-defined AITL several years after L-HES diagnosis, which thus raised the problem of the diagnosis of well-defined T-cell lymphoma in patients who have clonal circulating T cells.In this study, we focused on the lymphoid infiltrates in lymph nodes, skin and other available biopsies of tissue involved in L-HES, to assess the presence of clonal T cells at diagnosis and during CD3 - CD4+ L-HES course. We secondly aimed to distinguish L-HES from AITL by comparing histopathological and immunophenotypic characteristics between both entities Methods PatientsTwenty-three hypereosinophilic syndrome (HES) patients with a documented presence of CD3 - CD4+ aberrant subset and a negative FIP1L1-PDGFRA fusion gene research are currently followed The clonal T-cell disease in CD3 -CD4 + L-HES haematologica | 2015; 100(8) 1087 © F e r r a t a S t o r t i F o u n d a t i o nSkin lesions in L-HES patients were pruritic papulo-nodular inpatients P1 and P2, pruritic papular lesions in patient P3, P5, P8, isolated pruritus in patients P7 and P9. Numbers in in the French Eosinophil Network. For the present study, 16 patients (P1-P16) were included, 12 of them had available tissue biopsies during L-HES course. All satisfied criteria for HES (n=15) or hypereosinophilia (HE) (n=1, P13, no organ damage or clinical manifestation) criteria in accordance with the latest up-dated consensus definitions.1 Main clinical characteristics are summarized in Table 1. For the 7 remaining patients, no complementary lymphocyte immunophenotyping was performed, no biopsy was performed (n=5) or biopsies were not available for analysis (n=2). The study was approved by the Lille Hospital Ethical Committee and carried out in accordance with the Declaration of Helsinki.Ten of these patients had bone marrow biopsies at CD3 -CD4 + L-HES diagnosis in order to exclude a T-cell lymphoma (Patients P2-4, P8, P9, P11, P12, P14-16) (data not shown). Four patients had lymph nodes biopsies for a suspicion of T-cell lymphoma during follow up (Patients P1, P3, P4 and P10). For this work, all their biopsies were retrieved for further investigation and for a centralized compared analysis to be made.Finally, Patients P4 and P16 developed a well-defined AITL during L-HES course (AITL/L-HES patients).Patient P4. Patient P4 was 18-years old when a CD3 -CD4 + L-HES diagnosis was made in 1999 and was previously reported by us. 26He presented with eczema-like lesions, rare episodes of angioedema and multiple adenopathy. Despite high circulating CD3 -CD4 + T-cell count (28 G/L), lymph node histological examination confirmed lymphoid reactive hyperplasia. As he was in really good G. Lefèvre ...

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CD9 is a cell surface protein and belongs to the tetraspanin family. Its role in carcinomagenesis has been widely studied in solid tumors but remains controversial, depending on the cancer type. Although CD9 seems to be associated with unfavorable outcome and disease progression in acute lymphoblastic leukemia (ALL), this marker has not yet been studied in acute myeloid leukemia (AML). First, we explored its prognostic role and its association with biological factors in a cohort of 112 AML patients treated with intensive chemotherapy. CD9 was expressed in 40% of AML and was associated with a favorable outcome (event‐free survival and relapse‐free survival) in univariate (P = 0.009 and P = 0.048, respectively) and multivariate (P = 0.004 and P = 0.039, respectively) analyses. Interestingly, CD9 expression was different between the more immature physiologic and AML cells (CD34+CD38−) as it was also expressed in AML on putative leukemic stem cells (LSCs) but not on hematopoietic stem cells (HSCs). Hence, CD9 could be a very relevant marker for minimal residual disease (MRD) monitoring in AML based on LSC targeting.