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Available data have proved insufficient to develop consensus recommendations on the prevention of thrombosis and bleeding in myelofibrosis (MF). We evaluated the incidence and risk factors of vascular complications in 1613 patients from the Spanish Myelofibrosis Registry. Over a total of 6981 patient-years at risk, 6.4% of the study population had at least one thrombotic event after MF diagnosis, amounting to an incidence rate of 1.65 per 100 patient-years. Prior history of thrombosis, the JAK2 mutation, and the intermediate-2/high-risk International Prognostic Scoring System (IPSS) categories conferred an increased thrombotic risk after adjustment for the risk-modifying effect of anti-thrombotic and cytoreductive treatments. History of thrombosis and the JAK2 mutation allowed us to pinpoint a group of patients at higher risk of early thrombosis. No decreased incidence of thrombosis was observed while patients were on anti-thrombotic or cytoreductive treatment. An increased risk of venous thrombosis was found during treatment with immunomodulatory agents. A total of 5.3% of patients had at least one episode of major bleeding, resulting in an incidence rate of 1.5 events per 100 patient-years. Patients in the intermediate-2/high-risk IPSS categories treated with anti-coagulants had an almost sevenfold increased risk of major bleeding. These findings should prove useful for guiding decision-making in clinical practice., (© 2022 British Society for Haematology and John Wiley & Sons Ltd.)

The present study assessed the criteria for initiating cytoreduction and response to conventional therapies in 1446 patients with essential thrombocythemia (ET), 267 (17%) of which were CALR-mutated. In low risk patients, time from diagnosis to cytoreduction was shorter in CALR-positive than in the other genotypes (2·8, 3·2, 7·4 and 12·5 years for CALR, MPL, JAK2V617F and TN, respectively, P < 0·0001). A total of 1104 (76%) patients received cytoreductive treatment with hydroxycarbamide (HC) (n = 977), anagrelide (n = 113), or others (n = 14). The estimated cumulative rates of complete haematological response (CR) at 12 months were 40 % and 67% in CALR and JAK2V617F genotypes, respectively. Median time to CR was 192 days for JAK2V617F, 343 for TN, 433 for MPL, and 705 for CALR genotypes (P < 0·0001). Duration of CR was shorter in CALR-mutated ET than in the remaining patients (P = 0·003). In CALR-positive patients, HC and anagrelide had similar efficacy in terms of response rates and duration. CALR-mutated patients developed resistance/intolerance to HC more frequently (5%, 23%, 27% and 15% for JAK2V617F, CALR, MPL and TN, respectively; P < 0·0001). In conclusion, conventional cytoreductive agents are less effective in CALR-mutated ET, highlighting the need for new treatment modalities and redefinition of haematologic targets for patients with this genotype., (© 2020 British Society for Haematology and John Wiley & Sons Ltd.)

Aim: To characterise the clinical and histological features of MPL -mutated essential thrombocythaemia (ET)., Patients and Methods: Bone marrow biopsies of 175 patients with ET were centrally reviewed according to the 2016 WHO classification, including 42 cases with MPL mutation, 98 JAK2 V617F-mutated and 35 CALR -mutated. Clinical and histological features were compared among the three genotypes included in the current 2016 WHO classification and among the different types of MPL mutations., Results: Patients with MPL -mutated ET were significantly older than those with the other genotypes. Haematological values at diagnosis were similar among MPL -mutated and CALR -mutated ET, with both genotypes showing higher platelet counts and lower haemoglobin values than ET with JAK2 V617F genotype. In the bone marrow, the median number of megakaryocytes was higher in MPL and CALR than in JAK2 V617F genotype (16, 19 and 14 megakaryocytes per ×20 power field, respectively, p=0.004). Histological features of prefibrotic myelofibrosis were rarely observed in MPL genotype, whereas sinusoidal hyperplasia, dense clusters of megakaryocytes and reticulin fibrosis were more frequent in CALR -mutated ET, with 11% of such cases fulfilling WHO 2016 histological criteria of prefibrotic myelofibrosis. With a median follow-up of 3.5 years, no significant differences were seen among genotypes regarding survival, vascular complications or myelofibrotic transformation. There were no significant differences in the clinical data or in the histological characteristics depending on the type of MPL mutation., Conclusion: MPL and CALR ET genotypes share clinical and histological characteristics. In contrast to CALR genotype, features of prefibrotic myelofibrosis are uncommon in MPL -mutated ET., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

The current consensus on the diagnosis, prognosis, and treatment of essential thrombocythemia (ET) is based on experts' recommendations. However, several aspects of the diagnosis of, prognosis of, and therapy for ET are still controversial. The Delphi method was employed with an expert panel of members of the Spanish Group of Ph-negative Myeloproliferative Neoplasms in order to identify the degree of agreement on the diagnosis, prognosis, and treatment of ET. Nine leading experts selected a total of 41 clinical hematologists with well-known expertise in ET. An electronic questionnaire was used to collect the questions rated in a four-step scale. The questions were grouped into four blocks: diagnosis, risk stratification, goals of therapy, and treatment strategy. After the first round consisting of 80 questions, a second round including 14 additional questions focused on the recommendations advocated by experts of the European LeukemiaNet in 2011 was analyzed. The median and mean values for the first and second rounds were calculated. A summary of the conclusions considered as the most representative of each block of questions is presented. The Delphi method is a powerful instrument to address the current approaches and controversies surrounding ET.

It is unclear whether anticoagulation guidelines intended for the general population are applicable to patients with polycythemia vera (PV) and essential thrombocythemia (ET). In the present study, the risk of thrombotic recurrence was analyzed in 150 patients with PV and ET treated with vitamin K antagonists (VKA) because of an arterial or venous thrombosis. After an observation period of 963 patient-years, the incidence of re-thrombosis was 4.5 and 12 per 100 patient-years under VKA therapy and after stopping it, respectively (P < 0.0005). After a multivariate adjustment for other prognostic factors, VKA treatment was associated with a 2.8-fold reduction in the risk of thrombotic recurrence. Notably, VKA therapy offset the increased risk of re-thrombosis associated with a prior history of remote thrombosis. Both the protective effect of VKA therapy and the predisposing factors for recurrence were independent of the anatomical site involved in the index thrombosis. Treatment periods with VKA did not result in a higher incidence of major bleeding as compared with those without VKA. These findings support the use of long-term anticoagulation for the secondary prevention of thrombosis in patients with PV and ET, particularly in those with history of remote thrombosis.

Hydroxyurea is a drug widely used to control myeloproliferative disorders, due in part to its relative lack of severe side effects. We present a case of acute interstitial pneumonitis in a patient who was treated with hydroxyurea for essential thrombocythemia. The clinical course suggests that the interstitial pneumonitis was induced by hydroxyurea. This is the first case of hydroxyurea-induced acute interstitial pneumonitis reported in the literature.

The case of a patient with the diagnosis of essential thrombocythemia is presented. Following treatment with melphalan during three years the patient presented clinical and radiologic data of pulmonary fibrosis. Thoracotomy with lung biopsy histologically proving fibrosis was performed. The patient developed a true histiocytic lymphoma afterwards. The rarity of pulmonary fibrosis induced by melphalan and the exceptional association of essential thrombocythemia and histiocytic lymphoma is emphasized. The characteristics of the latter disease, diagnostic difficulties and possible treatment are commented upon.