From the observation of atypical cells on blood smear to the diagnosis of mast cell leukemia: a case report in a 79 year old woman consulting for anemia.

Mast cell leukemia is an extremely rare disease, which belongs to the systemic mastocytosis group (WHO 2016). We are reporting the case of a 79-year-old woman, without any hematological particular history consulting for hyperthermia, repeated malaise and subacute anemia. Her clinical examination was normal. Unusual cells were seen on blood and bone marrow smears. They represent more than 10% of blood nucleated cells end more than 20% of the bone marrow nucleated cells. Bone marrow immunophenotyping was performed to characterize these cells. It revealed a cell subset expressing the surface antigens CD117, CD2 and CD25. This immunophenotypic profile is the hallmark of malignant mast cells. Then mast cell leukemia diagnosis could have been made and KIT gene sequencing highlighted the N822Y mutation in exon 17. The patient was initially treated with midostaurin, a tyrosine kinase inhibitor. Lack of therapeutic response and absence of the KIT D816V mutation led to switch to imatinib, following the latest scientific recommendations.

Burkitt cells on a peripheral blood smear: how to deal with?

The diagnosis of double hit lymphoma remains a challenge for the biologist for a good management of the patient. This new category of lymphoma "double hit" (DH) is part of a new entity of the WHO classification 2008: « Unclassifiable B lymphoma with features intermediate between diffuse large cell B lymphoma and Burkitt's lymphoma ¼. It is defined by the presence of a breakpoint at the locus 8q24 of the c-MYC gene associated with a recurrent translocation involving BCL2 genes primarily BCL6 or more rarely CCDN1 or BCL3 genes. These chromosomal alterations are not systematically screened at diagnosis, which can cause misdiagnosis and poor therapy management. These lymphomas DH have variable cytology and may be confused with Burkitt lymphoma (BL) or with diffuse large B-cell lymphoma (DLBCL). They have a very poor prognosis and are often resistant to chemotherapy. Their therapy and their prognosis are different from those of the BL or the DLBCL. This entity and its morphology as well as histology either immunophenotypic or cytogenetic characteristics must therefore be known to biologists, pathologists, and clinicians. Cooperation between the various actors in these disciplines is essential in case of atypical BL or DLBCL to lead to a precise classification of the pathology.

In vivo and in vitro sensitivity of blastic plasmacytoid dendritic cell neoplasm to SL-401, an interleukin-3 receptor targeted biologic agent.

Blastic plasmacytoid dendritic cell neoplasm is an aggressive malignancy derived from plasmacytoid dendritic cells. There is currently no accepted standard of care for treating this neoplasm, and therapeutic strategies have never been prospectively evaluated. Since blastic plasmacytoid dendritic cell neoplasm cells express high levels of interleukin-3 receptor α chain (IL3-Rα or CD123), antitumor effects of the interleukin-3 receptor-targeted drug SL-401 against blastic plasmacytoid dendritic cell neoplasm were evaluated in vitro and in vivo. The cytotoxicity of SL-401 was assessed in patient-derived blastic plasmacytoid dendritic cell neoplasm cell lines (CAL-1 and GEN2.2) and in primary blastic plasmacytoid dendritic cell neoplasm cells isolated from 12 patients using flow cytometry and an in vitro cytotoxicity assay. The cytotoxic effects of SL-401 were compared to those of several relevant cytotoxic agents. SL-401 exhibited a robust cytotoxicity against blastic plasmacytoid dendritic cell neoplasm cells in a dose-dependent manner. Additionally, the cytotoxic effects of SL-401 were observed at substantially lower concentrations than those achieved in clinical trials to date. Survival of mice inoculated with a blastic plasmacytoid dendritic cell neoplasm cell line and treated with a single cycle of SL-401 was significantly longer than that of untreated controls (median survival, 58 versus 17 days, P<0.001). These findings indicate that blastic plasmacytoid dendritic cell neoplasm cells are highly sensitive to SL-401, and support further evaluation of SL-401 in patients suffering from blastic plasmacytoid dendritic cell neoplasm.

[WHIM syndrome: presumptive diagnosis based on myelokathexis on bone marrow smear]. / Diagnostic de syndrome WHIM évoqué devant l'observation de myélokathexis.

The WHIM syndrome is a rare congenital immunodeficiency disorder characterized by human papillomavirus (HPV)-induced warts, hypogammaglobulinemia, bacterial infections and myelokathexis. Myelokathexis refers to abnormal retention of mature neutrophils in the bone marrow leading to severe neutropenia. We report the case of a 20 year old man presenting with chronic and severe neutropenia since early childhood without established diagnosis. He was addressed for chronic parodontal disease treatment. Examination of bone marrow smear showed morphological abnormalities of mature neutrophils strongly suggestive of myelokathexis. Diagnosis of WHIM syndrome was confirmed by molecular analysis: a nonsense mutation was identified in the gene encoding CXCR4, the CXCL12 (or SDF-1) chemokine receptor which notably controls cell adhesion to the marrow stroma and thereby regulates mature leukocytes release from the bone marrow. Treatment of the disease usually consists in prophylactic anti-infective measures including intravenous immunoglobulins administration, oral antibiotic prophylaxis and more recently HPV vaccination. Long term G-CSF therapy did not show any significant efficiency in preventing recurrent infections. The use of specific CXCR4 antagonist is being currently evaluated.

Epigenetic control of NF-κB-dependent FAS gene transcription during progression of myelodysplastic syndromes.

The death domain containing TNF receptor 6 (CD95/Fas) is a direct target for the NF-κB transcription factor and is repressed in solid tumors such as colon carcinomas. Previously, we reported that the Fas death receptor, while overexpressed in low-risk myelodysplastic syndromes (MDS), becomes undetectable on CD34(+) progenitors when the disease progresses to secondary acute myeloid leukemia (AML). This study determined the interplay between NF-κB and Fas during MDS progression. We first observed that Fas was induced by TNF-α in the HL60 cell line. In these cells, p65 (RELA) was associated with the FAS promoter, and inhibition of the NF-κB pathway by an IKKα inhibitor (BAY11-7082) or lentiviral expression of a nondegradable mutant of IκBα (IκSR) blocked Fas expression. In contrast, TNF-α failed to induce Fas expression in the colon carcinoma cell line SW480, due to hypermethylation of the FAS promoter. Azacitidine rescued p65 binding on FAS promoter in vitro, and subsequently Fas expression in SW480 cells. Furthermore, inhibition of the NF-κB pathway decreased the expression of Fas in MDS CD45(lo)CD34(+) bone marrow cells. However, despite the nuclear expression of p65, Fas was often low on CD45(lo)CD34(+) AML cells. TNF-α failed to stimulate its expression, while azacitidine efficiently rescued p65 binding and Fas reexpression. Overall, these data suggest that DNA methylation at NF-κB sites is responsible for FAS gene silencing.

[Usefulness of gray platelets observation in ARC syndrome]. / ARC syndrome et observation de plaquettes grises: utilité diagnostique.

Arthrogryposis Renal Fanconi syndrome and Cholestasis (ARC syndrome) is an extremely rare disease (62 cases) and is uneasy to diagnose. This congenital multisystem disorder affects newborns who usually die in the first year of life. The three cases here report the main clinical and biological features of this unknown disease and show how careful platelets morphology examination on blood smear can help for diagnosis. The three cases were observed at Robert Debré hospital in Paris over a twenty years period. In the first case, ARC syndrome was diagnosed after death. For the two following newborns, gray platelets detection in association with clinical symptoms allowed an earlier diagnosis.