Blastic plasmacytoid dendritic cell neoplasm with leukemic presentation: 10-Color flow cytometry diagnosis and HyperCVAD therapy.

Few studies describe the comprehensive immunophenotypic pattern of blastic plasmacytoid dendritic cell neoplasm (BPDCN) in the bone marrow and its treatment. This retrospective analysis evaluates the diagnostic flow cytometry (FCM) pattern and outcome of nine patients diagnosed with BPDCN. A four-tube 10-color FCM panel used for diagnosis of acute leukemia (AL), showed cells in the blast gate (CD45dim/low SSC) and were positive for CD4(bright), CD33(dim), CD56(heterogenous), CD123(bright), CD36, CD38, HLA-DR, CD71. Seven patients received front-line induction therapy with HyperCVAD with an overall response rate of 86%. Five of six responders underwent planned allogeneic hematopoietic cell transplantation (allo-HCT). For a median follow up of 13.3 months, the 1-year disease free survival and overall survival were 56 and 67%, respectively. An accurate diagnosis of BPDCN can be made by 10-color FCM using a four-tube AL panel demonstrating a characteristic pattern of antigen expression. Front-line induction chemotherapy with HyperCVAD can yield high remission rates, but allo-HCT is required for long-term durable remissions.

Radar plots facilitate differential diagnosis of acute promyelocytic leukemia and NPM1+ acute myeloid leukemia by flow cytometry.

BACKGROUND: Acute promyelocytic leukemia (APL) is one of the most life-threatening hematological emergencies and requires a prompt correct diagnosis by cytomorphology and flow cytometry (FCM) with later confirmation by cytogenetics/molecular genetics. However, nucleophosmin 1 muted acute myeloid leukemia (NPM1+ AML) can mimic APL, especially the hypogranular variant of APL. Our study aimed to develop a novel, Radar plot-based FCM strategy to distinguish APLs and NPM1+ AMLs quickly and accurately. METHOD: Diagnostic samples from 52 APL and 32 NPM1+ AMLs patients were analyzed by a 3-tube panel of 10-color FCM. Radar plots combining all markers were constructed for each tube. Percentages of positive leukemic cells and mean fluorescence intensity were calculated for all the markers. RESULTS: APL showed significantly higher expression of CD64, CD2, and CD13, whereas more leukemic cells were positive for CD11b, CD11c, CD15, CD36, and HLA-DR in NPM1+ AMLs. Radar plots featured CD2 expression, a lack of a monocytic component, lack of expression of HLA-DR and CD15, and a lack of a prominent CD11c+ population as recurring characteristics of APL. The presence of blasts with low SSC, presence of at least some monocytes, some expression of HLA-DR and/or CD15, and a prominent CD11c population were recurrent characteristics of NPM1+ AMLs. Radar plot analysis could confidently separate all hypergranular APL cases from any NPM1+ AML and in 90% of cases between variant APL and blastic NPM1+ AML. CONCLUSION: Radar plots can potentially add to differential diagnostics as they exhibit characteristic patterns distinguishing APL and different types of NPM1+ AMLs.

Role of CD47 in Hematological Malignancies.

CD47, or integrin-associated protein, is a cell surface ligand expressed in low levels by nearly all cells of the body. It plays an integral role in various immune responses as well as autoimmunity, by sending a potent "don't eat me" signal to prevent phagocytosis. A growing body of evidence demonstrates that CD47 is overexpressed in various hematological malignancies and its interaction with SIRPα on the phagocytic cells prevents phagocytosis of cancer cells. Additionally, it is expressed by different cell types in the tumor microenvironment and is required for establishing tumor metastasis. Overexpression of CD47 is thus often associated with poor clinical outcomes. CD47 has emerged as a potential therapeutic target and is being investigated in various preclinical studies as well as clinical trials to prove its safety and efficacy in treating hematological neoplasms. This review focuses on different therapeutic mechanisms to target CD47, either alone or in combination with other cell surface markers, and its pivotal role in impairing tumor growth and metastatic spread of various types of hematological malignancies.

Visualization of Cell Composition and Maturation in the Bone Marrow Using 10-Color Flow Cytometry and Radar Plots.

BACKGROUND: The enormous potential of complex data files generated by 10-color flow cytometry (FC) is hindered by the requirement for exhaustive manual gating and the complexity of multidimensional data visualization. We propose a model using radar plots (RPs), to improve FC data visualization by capturing multidimensionality and integration of FC findings. METHOD: We analysed 12 normal/reactive bone marrow (N/R BM) samples and 12 BM samples from patients with myelodysplasia (MDS) with 10-color FC. All identifiable cell clusters were individually marked, grouped, and visualized on radar plots. RPs were optimized to de-clutter the cell clusters and map BM cell composition and maturation. RESULTS: A total of 27 immature and mature cell clusters were identified and visualized on 8 multidimensional radar plots. The RPs displayed flow cytometry findings of normal BM in an integrated fashion to maximize overall insight into the data set. The constructed map of bone marrow cell composition was reproducible in all normal BM samples analyzed. Analysis of the pilot cohort of patient samples confirmed the presence of MDS-related changes. These changes are readily identifiable on RPs. CONCLUSION: We demonstrated that the cell clusters of normal BM can be mapped on multidimensional radar plots, which provide an inclusive insight into BM cell composition and maturation. These reproducible RPs present a comprehensive and comprehensible visual display of differentiation and maturation of haematopoietic cells in normal BM, and can be used as a reference map to assess abnormal haematopoiesis in MDS. © 2017 International Clinical Cytometry Society.

Intrathoracic Rosai Dorfman Disease with Focal Aggregates of IgG4-bearing Plasma Cells. Case Report and Literature Review.

Rosai Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare histiocytic disorder that typically presents as painless cervical adenopathy. Occasionally, Rosai Dorfman disease may involve extranodal sites and it can be associated with constitutional symptoms. In this report, we present a patient with progressive dyspnea on exertion, obstruction on spirometry, and paratracheal soft tissue thickening extending to the proximal bronchi and hila. After extensive radiologic and interventional measures, including multiple biopsies, the diagnosis was established on pathology showing characteristic features of Rosai Dorfman disease in a paratracheal lymph node and features of extranodal Rosai Dorfman disease with extensive fibrosis in the paratracheal mass. In addition, the involved paratracheal lymph node demonstrated focally increased IgG4-positive plasma cells, a finding that was not present in the tracheal mass. A review of intrathoracic manifestations of Rosai Dorfman disease including the proposed causes and causative triggers is presented. The histological features and the current understanding of the management and prognosis are also discussed. This unusual presentation highlights the need to consider histiocytic disorders in the differential diagnosis of paratracheal disease.