The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CAC) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

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Background and Objectives This study explored variations in the clinical manifestations of intravascular lymphoma (IVL) on the bases of the association with hemophagocytosis and the country where the diagnosis was made. Design and Methods The clinical features of 50 Western patients with IVL were compared with those of 123 patients with IVL diagnosed in Eastern countries (87 diagnosed in Japan and 36 in other Asian countries), previously reported in English literature, and collected by an electronic bibliographic search. Results Hemophagocytosis was absent in Western patients, but reported in 38 (44%) Japanese patients (p=0.00001) and in seven (19%) patients from other Asian countries (p=0.002). No clinical differences were evident between patients with hemophagocytosis-negative IVL diagnosed in Western countries, Japan and other Asian Countries. Conversely, Japanese and non-Japanese patients with hemophagocytosisrelated IVL more frequently had stage IV disease, fever, hepato-splenic involvement, marrow infiltration, dyspnea, anemia, and thrombocytopenia, and rarely exhibited cutaneous or central nervous system involvement. Lymph node and peripheral blood involvement was uncommon in all subgroups. In Western patients, anthracycline-based chemotherapy was associated with a 52% remission rate, and a 2-year overall survival of 46%. Interpretation and Conclusions The clinical features of IVL vary according to the association with hemophagocytosis, regardless of the country in which the diagnosis is made. Western, Japanese and other Asian patients with hemophagocytosis-negative IVL display similar clinical characteristics and should be considered as having classical IVL. Patients with hemophagocytosis-related IVL show significantly different clinical features. Both forms have a poor prognosis. Extensive molecular studies are needed to explore whether these clinical differences might reflect discordant biological entities within IVL

MBL is an aggressive NHL with unique clinicopathologic aspects, often refractory to current CHT designed for high-grade NHL. Poor performance status and pericardial effusion predict NR and poor survival. Inadequate response after the first courses of front-line CHT predicts failure of subsequent treatment. Responders with bulky mediastinum or residual mediastinal abnormality after CHT are at risk of relapse. These factors should help to select high-risk patients for intensive treatments.

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Extracellular matrix (ECM) components initiate crucial biochemical and biomechanical cues that are required for bone marrow homeostasis. In our research, we prove that a peri-cellular matrix composed primarily of type III and type IV collagens, and fibronectin surrounds human megakaryocytes in the bone marrow. The data we collected support the hypothesis that bone marrow megakaryocytes possess a complete mechanism to synthesize the ECM components, and that thrombopoietin is a pivotal regulator of this new function inducing transforming growth factor-b1 (TGF-b1) release and consequent activation of the downstream pathways, both in vitro and in vivo. This activation results in a dose dependent increase of ECM component synthesis by megakaryocytes, which is reverted upon incubation with JAK and TGF-b1 receptor specific inhibitors. These data are pivotal for understanding the central role of megakaryocytes in creating their own regulatory niche within the bone marrow environment. STEM CELLS 2016;34:1123-1133 SIGNIFICANCE STATEMENTBone marrow is a finely organized organ formed by extracellular matrix (ECM) components and various cell types. Increasing evidences are highlightening the importance of the ECM components in the regulation of different aspects of cell behavior. In this regard, we recently demonstrated that mouse megakaryocytes, the bone marrow resident platelet progenitors, are able to produce ECM components which in turn regulate their function. Here we extend this observation by describing the mechanism by which human and mouse megakaryocytes produce those ECM components in vitro and in vivo.

We reviewed a large series of patients with essential thrombocythemia diagnosed on the basis of the Polycythemia Vera Study Group criteria, and reclassified them by evaluating their major morphologic features and clinical course using the World Health Organization classification. The morphologic review of the bone marrow biopsies of 116 patients (44 males and 72 females; aged 19 - 83 years, median 55 years; median follow-up 121 months) led to 22 cases (19%) being classified as essential thrombocythemia (ET), 24 (21%) as chronic idiopathic myelofibrosis (CIMF)-0, 44 (37%) as CIMF-1, 13 (12%) as CIMF-2, 9 (8%) as latent phase polycythemia vera, and four (3%) as chronic myeloproliferative disorder, unclassifiable. There was a significant difference in the median age of the ET and fibrotic CIMF patients (54.7 +/- 13.55 vs. 59.13 +/- 15.05 years; P = 0.03). Histologic analysis showed that the simultaneous presence of loose clusters of large/giant megakaryocytes and nuclear hyperlobulation was significantly different between the ET and the prefibrotic CIMF (P<0.01) and fibrotic CIMF patients (P<0.01), and that the association of dense clusters of megakaryocytes with maturation defects and bulbous nuclei also distinguished the prefibrotic CIMF (P<0.05) and fibrotic CIMF patients (P<0.001) from those with ET. The association of cellularity, granulocytic proliferation and reticulin fibers was helpful in distinguishing prefibrotic from fibrotic CIMF (P<0.001).