B-ALL With t(5;14)(q31;q32); IGH-IL3 Rearrangement and Eosinophilia: A Comprehensive Analysis of a Peculiar IGH-Rearranged B-ALL

Background: B-cell acute lymphoblastic leukemia associated with t(5;14)(q31;q32); IGH-IL3 is an exceptional cause of eosinophilia. The IGH enhancer on 14q32 is juxtaposed to the IL3 gene on 5q31, leading to interleukin-3 overproduction and release of mature eosinophils in the blood. Clinical, biological and outcome data are extremely scarce in the literature. Except for eosinophilia, no relevant common feature has been highlighted in these patients. However, it has been classified as a distinct entity in the World Health Organization classification.

Cases Presentation: Eight patients with t(5;14)(q31;q32) treated by French or Austrian protocols were retrospectively enrolled. Array comparative genomic hybridization, multiplex ligation-dependent probe amplification or genomic PCR search for IKZF1 deletion were performed in 7. Sixteen patients found through an exhaustive search in the literature were also analyzed.

For those 24 patients, median age at diagnosis is 14.3 years with a male predominance (male to female ratio = 5). Eosinophilia-related symptoms are common (neurologic in 26%, thromboembolic in 26% or pulmonary in 50%). Median white blood cells count is high (72 × 10⁹/L) and linked to eosinophilia (median: 32 × 10⁹/L). Peripheral blasts are present at a low level or absent (median: 0 × 10⁹/L; range: 0–37 × 10⁹/L). Bone marrow morphology is marked by a low blast infiltration (median: 42%). We found an IKZF1 deletion in 5 out of 7 analyzable patients Outcome data are available for 14 patients (median follow-up: 28 months): 8 died and 6 are alive in complete remission.

Some of these features are concordant with those seen in patients with other IGH-rearranged B-cell acute lymphoblastic leukemias: young age at onset, male sex, low blast count, high incidence of IKZF1 deletion and intermediate prognosis.

Conclusion: Based on shared epidemiological and biological features, B-cell acute lymphoblastic leukemia with t(5;14)(q31;q32) is a peculiar subset of IGH-rearranged B-cell acute lymphoblastic leukemia with an intermediate prognosis and particular clinical features related to eosinophilia.

CD9 in acute myeloid leukemia: Prognostic role and usefulness to target leukemic stem cells

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.

Database-guided Flow-cytometry for Evaluation of Bone Marrow Myeloid Cell Maturation

A working group initiated within the French Cytometry Association (AFC) was developed in order to harmonize the application of multiparameter flow cytometry (MFC) for myeloid disease diagnosis in France. The protocol presented here was agreed-upon and applied between September 2013 and November 2015 in six French diagnostic laboratories (University Hospitals of Saint-Etienne, Grenoble, Clermont-Ferrand, Nice, and Lille and Institut Paoli-Calmettes in Marseille) and allowed the standardization of bone marrow sample preparation and data acquisition. Three maturation databases were developed for neutrophil, monocytic, and erythroid lineages with bone marrow from "healthy" donor individuals (individuals without any evidence of a hematopoietic disease). A robust method of analysis for each myeloid lineage should be applicable for routine diagnostic use. New cases can be analyzed in the same manner and compared against the usual databases. Thus, quantitative and qualitative phenotypic abnormalities can be identified and those above 2SD compared with data of normal bone marrow samples should be considered indicative of pathology. The major limitation is the higher variability between the data achieved using the monoclonal antibodies obtained with the methods based on hybridoma technologies and currently used in clinical diagnosis. Setting criteria for technical validation of the data acquired may help improve the utility of MFC for MDS diagnostics. The establishment of these criteria requires analysis against a database. The reduction of investigator subjectivity in data analysis is an important advantage of this method.

CD3-CD4+ lymphoid variant of hypereosinophilic syndrome: nodal and extranodal histopathological and immunophenotypic features of a peripheral indolent clonal T-cell lymphoproliferative disorder

The CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome is characterized by hypereosinophilia and clonal circulating CD3(-)CD4(+) T cells. Peripheral T-cell lymphoma has been described during this disease course, and we observed in our cohort of 23 patients 2 cases of angio-immunoblastic T-cell lymphoma. We focus here on histopathological (n=12 patients) and immunophenotypic (n=15) characteristics of CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome. Atypical CD4(+) T cells lymphoid infiltrates were found in 10 of 12 CD3(-)CD4(+) L-HES patients, in lymph nodes (n=4 of 4 patients), in skin (n=9 of 9) and other extra-nodal tissues (gut, lacrymal gland, synovium). Lymph nodes displayed infiltrates limited to the interfollicular areas or even an effacement of nodal architecture, associated with proliferation of arborizing high endothelial venules and increased follicular dendritic cell meshwork. Analysis of 2 fresh skin samples confirmed the presence of CD3(-)CD4(+) T cells. Clonal T cells were detected in at least one tissue in 8 patients, including lymph nodes (n=4 of 4): the same clonal T cells were detected in blood and in at least one biopsy, with a maximum delay of 23 years between samples. In the majority of cases, circulating CD3(-)CD4(+) T cells were CD2(hi) (n=9 of 14), CD5(hi) (n=12 of 14), and CD7(-)(n=4 of 14) or CD7(low) (n=10 of 14). Angio-immunoblastic T-cell lymphoma can also present with CD3(-)CD4(+) T cells; despite other common histopathological and immunophenotypic features, CD10 expression and follicular helper T-cell markers were not detected in lymphoid variant of hypereosinophilic syndrome patients, except in both patients who developed angio-immunoblastic T-cell lymphoma, and only at T-cell lymphoma diagnosis. Taken together, persistence of tissular clonal T cells and histopathological features define CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome as a peripheral indolent clonal T-cell lymphoproliferative disorder, which should not be confused with angio-immunoblastic T-cell lymphoma.