Standardization of Flow Cytometric Immunophenotyping for Hematological Malignancies: The FranceFlow Group Experience.

Flow cytometry is broadly used for the identification, characterization, and monitoring of hematological malignancies. However, the use of clinical flow cytometry is restricted by its lack of reproducibility across multiple centers. Since 2006, the EuroFlow consortium has been developing a standardized procedure detailing the whole process from instrument settings to data analysis. The FranceFlow group was created in 2010 with the intention to educate participating centers in France about the standardized instrument setting protocol (SOP) developed by the EuroFlow consortium and to organise several rounds of quality controls (QCs) in order to evaluate the feasibility of its application and its results. Here, we report the 5 year experience of the FranceFlow group and the results of the seven QCs of 23 instruments, involving up to 19 centers, in France and in Belgium. The FranceFlow group demonstrates that both the distribution and applicability of the SOP have been successful. Intercenter reproducibility was evaluated using both normal and pathological blood samples. Coefficients of variation (CVs) across the centers were <7% for the percentages of cell subsets and <30% for the median fluorescence intensities (MFIs) of the markers tested. Intracenter reproducibility provided similar results with CVs of <3% for the percentages of the majority of cell subsets, and CVs of <20% for the MFI values for the majority of markers. Altogether, the FranceFlow group show that the 19 participating labs might be considered as one unique laboratory with 23 identical flow cytometers able to reproduce identical results. Therefore, SOP significantly improves reproducibility of clinical flow in hematology and opens new avenues by providing a robust companion diagnostic tool for clinical trials in hematology. © 2019 International Society for Advancement of Cytometry.

Paediatric anaplastic large cell lymphoma with leukaemic presentation in children: a report of nine French cases.

This study aimed to describe the clinical features and outcome of anaplastic large cell lymphoma (ALCL) with leukaemic presentation in children. Among 267 patients included in the French paediatric ALCL database between 1989 and 2012, nine (3%) were described as having cytologically detectable circulating tumour cells. Clinical features combined fever (8/9), nodal and extra-nodal disease (9/9), including hepato-splenic (9/9) and lung involvement (7/9). The level of hyperleucocytosis ranged from 30 to 120 × 10(9) /l, with 12-90% of tumour cells. Diagnosis relied on a lymph node biopsy, with a positive ALK+ antibody immunostain in all nine cases, a T-cell immunophenotype in 7/9 cases and CD3 positivity in 5/9 cases. A small cell component was present in 6/9 cases. Only four patients achieved a complete remission with first-line therapy and 3/4 relapsed. Four patients are alive with a median follow-up of 31 months, two of them after allogeneic haematopoietic stem cell transplantation (HSCT), and five patients died, two of them of disease. In conclusion, ALCL with leukaemic presentation is very unusual and should be considered as high-risk lymphoma requiring new therapeutic strategies. The respective role of new agents and allogeneic HSCT in first complete remission still has to be assessed.

A cytogenetic study of 397 consecutive acute myeloid leukemia cases identified three with a t(7;21) associated with 5q abnormalities and exhibiting similar clinical and biological features, suggesting a new, rare acute myeloid leukemia entity.

The RUNX1 gene is implicated in numerous chromosomal translocations that occur in acute myeloid leukemia (AML) and result in chimeric genes. In this study, 397 consecutive AML cases were analyzed using RUNX1 fluorescence in situ hybridization (FISH) probes. Three cases of the recently described translocation, t(7;21)(p22;q22), were identified, which expressed RUNX1-USP42 (ubiquitin-specific protease 42) fusion transcripts, associated with 5q abnormalities and hyperploidy. These cases displayed homogeneous morphological features (including phagocytosis) and aberrantly expressed CD56 and CD7 lymphoid antigens. Although very few data are available from previously reported cases, when these features are present, a detailed chromosomal analysis, including hybridization with RUNX1 FISH probes, should be performed at diagnosis to recognize chromosomal abnormalities. Additional cases of t(7;21) positive AML should be evaluated to characterize this potentially rare AML entity in greater detail.

Mutual benefits of B-ALL and HLDA/HCDM HLDA 9th Barcelona 2010.

The B-cell panel of the ninth HLDA was applied in a multicentre fashion to cryopreserved cells from 46 patients with acute lymphoblastic leukemia. The reagents were aliquoted and shipped to volunteer participants from the French Groupe d'Etude Immunologique des Leucémies (GEIL). All samples were tested in flow cytometry, and the results collected as of the strength of labeling of the leukemic clone as negative, weak or strong. Among the 64 antibodies tested, the strongest and most frequent staining was observed for CD305 (LAIR), CD229 (Ly9), CD200 (OX-2) and, to a lesser extent, CD361 (EVI2b). Details of the observations, and information about the molecules tested are provided in the manuscript as well as a summary table.