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Background: Refractory anemia with ring sideroblasts associated with marked thrombocytosis was proposed as a provisional entity in the 2001 World Health Organization classification of myeloid neoplasms and also in the 2008 version, but its existence as a single entity is contested. We wish to define the clinical features of this rare myelodysplastic/myeloproliferative neoplasm and to compare its clinical outcome with that of refractory anemia with ring sideroblasts and essential thrombocythemia., Design and Methods: We conducted a collaborative retrospective study across Europe. Our database included 200 patients diagnosed with refractory anemia with ring sideroblasts and marked thrombocytosis. For each of these patients, each patient diagnosed with refractory anemia with ring sideroblasts was matched for age and sex. At the same time, a cohort of 454 patients with essential thrombocythemia was used to compare outcomes of the two diseases., Results: In patients with refractory anemia with ring sideroblasts and marked thrombocytosis, depending on the Janus Kinase 2 V617F mutational status (positive or negative) or platelet threshold (over or below 600 × 10(9)/L), no difference in survival was noted. However, these patients had shorter overall survival and leukemia-free survival with a lower risk of thrombotic complications than did patients with essential thrombocythemia (P<0.001) but better survival (P<0.001) and a higher risk of thrombosis (P=0.039) than patients with refractory anemia with ring sideroblasts., Conclusions: The clinical course of refractory anemia with ring sideroblasts and marked thrombocytosis is better than that of refractory anemia with ring sideroblasts and worse than that of essential thrombocythemia. The higher risk of thrombotic events in this disorder suggests that anti-platelet therapy might be considered in this subset of patients. From a clinical point of view, it appears to be important to consider refractory anemia with ring sideroblasts and marked thrombocytosis as a distinct entity.

Unlabelled: Background The MPL(Ser505Asn) mutation has been reported to be a cause of hereditary thrombocythemia. Recently, we detected this mutation in a large proportion of children with familial thrombocythemia, suggesting that in Italy the incidence of MPL(Ser505Asn) mutation could be underestimated., Design and Methods: We extended the search for this mutation to all patients with essential thrombocythemia who had a positive family history for thrombocytosis or essential thrombocythemia. We identified eight Italian families positive for the MPL(Ser505Asn) mutation. Clinical and hematologic data were available for members of seven families, including 21 patients with a proven mutation and 20 relatives with thrombocytosis., Results: Fifteen major thrombotic episodes, nine of which were fatal, were recorded among 41 patients. The thrombotic manifestation was stroke in four cases, myocardial infarction in seven cases, fetal loss in two cases, deep vein thrombosis of the leg in one case and Budd Chiari syndrome in one case. Almost all patients over 20 years old had splenomegaly and bone marrow fibrosis, while these were rarely observed in patients under 20 years old, suggesting that these manifestations are associated with aging. Finally, the life expectancy of family members with thrombocytosis was significantly shorter than that of members without thrombocytosis (P=0.003). Conclusions Patients with familial thrombocytosis caused by a MPL(Ser505Asn) mutation have a high risk of thrombosis and, with aging, develop splenomegaly and bone marrow fibrosis, significantly affecting their life expectancy.

Background and Objectives: Previous retrospective studies have indicated markedly increased bone marrow angiogenesis (BMA) in myelofibrosis with myeloid metaplasia (MMM). This issue is further examined in the current prospective study and clinico-pathological correlates sought., Design and Methods: This was a prospective single institutional study of 66 patients with bone marrow biopsy-proven MMM who were consecutively accrued. Bone marrow angiogenesis was evaluated by assessing microvessel density through immunohistochemical staining for the CD34 antigen. Laboratory and clinical information was collected concurrently., Results: The 66 patients (median age 62 years, 46 males) included 36 with fibrotic phase agnogenic myeloid metaplasia (AMM), 6 with cellular phase AMM, 4 with hypocellular variant AMM, 10 with post-polycythemic myeloid metaplasia, and 10 with post-thrombocythemic myeloid metaplasia. Overall, increased BMA was documented in 61 patients (92%). All of the aforementioned sub-categories of MMM were similarly affected in terms of either grade 3 or 4 BMA but differed in the prevalence of grade 4 BMA (25%, 0%, 0%, 10%, and 10%, respectively). In a univariate analysis the only histological feature that significantly correlated with BMA was the degree of megakaryocyte clustering. Among clinical features, increased BMA was significantly associated with younger age of the patient, lower hemoglobin level, intact spleen, and absence of active therapy. On multivariate analysis, only the latter two retained their significance., Interpretation and Conclusions: The current prospective study confirms the consistent association of BMA with MMM and suggests that the process starts early, is progressive, and might be dampened by both splenectomy and drug therapy. The study also suggests either a megakaryocyte origin or a megakaryocyte effect for the putative angiogenic cytokine.

Background and Objective: The distinction between clonal and reactive thrombocytoses is a frequent problem and implies different therapeutic options. As thrombopoietin (TPO) is the main regulator of megakaryocytopoiesis and thrombopoiesis, we measured TPO levels in patients with thrombocytosis in an attempt to understand the regulation and potential utility of distinguishing thrombocytoses., Design and Methods: Serum TPO levels, platelet counts, mean platelet volume, hemoglobin, erythrocyte sedimentation rate and age were evaluated in 25 patients with clonal thrombocytosis (15 with essential thrombocythemia, 6 with polycythemia vera and 4 with chronic myeloid leukemia) and in 50 patients with reactive thrombocytosis distributed in three groups: 1) patients in post-surgical states; 2) patients with solid tumors; and 3) patients with inflammatory diseases., Results: TPO levels were slightly increased in patients with clonal (135+/-50 pg/mL) and reactive (147+/-58 pg/mL) thrombocytosis compared with controls (121+/-58 pg/mL). Analyzing the different groups, patients with essential thrombocythemia had the lowest TPO levels (120+/-28 pg/mL) and patients with solid tumors the highest levels (162+/-59 pg/mL). Patients with clonal thrombocytosis were older, had higher platelet counts, mean platelet volume and hemoglobin, and lower erythrocyte sedimentation rate than patients with reactive thrombocytosis., Interpretation and Conclusions: Minor differences were observed in TPO levels between patients with primary and secondary thrombocytoses. Erythrocyte sedimentation rate, but not TPO levels, may be a useful tool for discriminating both types of thrombocytoses.

Background and Methods: Polycythemia vera (PV) and essential thrombocythemia (ET) in young patients are rarely reported. Their natural histories seem to differ from those of older patients and the best treatment is still uncertain. In this follow-up study we have evaluated a cohort of 64 consecutive patients younger than 40 to determine the incidence of thrombohemorrhagic events and the long-term outcome., Results: Twenty-eight patients (20 M; 8 F) had PV, and 36 ET (21 F, 15 M). Mean follow-up was 8.2 years (range 4 months-16.7 years) in PV and 6.5 years (range 5 months-15 years) in ET. Thrombohemorrhagic symptoms were present at diagnosis in 10/28 patients (35%) with PV and in 12/36 patients (33%) with ET; during follow-up in 15/28 PV patients (53%) and in 13/36 ET patients (36%). Thrombotic events were the most frequent symptoms, both at diagnosis (52% in PV, 65% in ET) and during follow-up (43% in PV, 52% in ET). A total of 19/28 PV patients (67%) and 17/36 ET patients (47%) had thrombotic complications. Hemorrhagic complications at diagnosis were 4% and during follow-up 13% in PV, and 15% and 13% in ET. A total of 5/28 (18%) PV and 6/36 (17%) ET patients had hemorrhagic events. No laboratory parameter, including platelet count, was predictive of these events. Five PV patients had major thrombotic complications (18%). Four PV patients died (14%), 2 because of ANLL (7%), 2 because of thrombotic events (7%). Four ET patients experienced major complications, in three cases thrombotic (8.3%), in one hemorrhagic. No leukemic transformation occurred in ET and no ET patient died., Conclusions: In our experience, severe thrombohemorrhagic complications are present in young patients with PV and ET, which excludes young age as a favorable prognostic factor. Treatment also seems advisable for young patients and myelosuppressive treatment might be required. Prospective studies are urgently needed to assess the best treatment for this particular subset of patients.

Background: The major causes of morbidity and mortality in essential thrombocythemia (ET) are bleeding and thrombotic accidents, but a prognostic pattern for these complications has not yet been discovered., Materials and Methods: In this study we report data from a large cohort of patients with thrombocytosis, distinguished for sex and age, in order to define their thrombotic risk. The prevalence of vascular complications recognized in 86 patients with essential thrombocythemia was studied. In addition, 91 patients with polycythemia vera (PV), 20 with myelofibrosis (MF) and 63 with secondary thrombocytosis (ST) were evaluated., Results: 6.3% of ET subjects younger than 40 (4.6% of males and 7.0% of females), 11.8% of patients between 40 and 65 years old (14.9% of males and 9% of females), and 16.8% of subjects over 65 (14.6% of males and 17.8% of females) showed thrombotic accidents. In the PV and MF groups thromboses occurred more frequently than in the ET groups for all ages and for both sexes. On the contrary, ST subjects showed fewer thromboses than ET patients, but their incidence rose with patient age; moreover the prevalence of males in this group was limited. In ET patients, particularly in females, the incidence of thrombosis was low under 40 years of age, but rapidly increased later., Conclusions: ET females over 40 must be followed with particular attention in order to prevent thrombotic complications.