Cerebral venous thrombosis and myeloproliferative neoplasms: results from two large databases

Exploring the Molecular Aspects of Myeloproliferative Neoplasms Associated with Unusual Site Vein Thrombosis: Review of the Literature and Latest Insights

Myeloproliferative neoplasms (MPNs) are the leading causes of unusual site thrombosis, affecting nearly 40% of individuals with conditions like Budd-Chiari syndrome or portal vein thrombosis. Diagnosing MPNs in these cases is challenging because common indicators, such as spleen enlargement and elevated blood cell counts, can be obscured by portal hypertension or bleeding issues. Recent advancements in diagnostic tools have enhanced the accuracy of MPN diagnosis and classification. While bone marrow biopsies remain significant diagnostic criteria, molecular markers now play a pivotal role in both diagnosis and prognosis assessment. Hence, it is essential to initiate the diagnostic process for splanchnic vein thrombosis with a JAK2 V617F mutation screening, but a comprehensive approach is necessary. A multidisciplinary strategy is vital to accurately determine the specific subtype of MPNs, recommend additional tests, and propose the most effective treatment plan. Establishing specialized care pathways for patients with splanchnic vein thrombosis and underlying MPNs is crucial to tailor management approaches that reduce the risk of hematological outcomes and hepatic complications.

Pathophysiology, diagnosis and management of cerebral venous thrombosis: A comprehensive review

Cerebral venous thrombosis is a rare cause of stroke in young mostly female adults which is frequently overlooked due to its variable clinical and radiological presentation. This review summarizes current knowledge on it risk factors, management and outcome in adults and highlights areas for future research. Females are 3 times more commonly affected and are significantly younger than males. The presenting symptoms can range from headache to loss of consciousness. However, the often-nebulous nature of symptoms can make the diagnosis challenging. Magnetic resonance imaging with venography is often the diagnostic imaging of choice. While unfractionated or low molecular-weight heparin is the mainstay of treatment, endovascular intervention with thrombolysis or thrombectomy and decompressive craniectomy may be required depending on clinical status. Nevertheless, approximately 80% of patients have a good recovery but mortality rates of -5% to 10% are not uncommon. Diagnosing cerebral venous thrombosis can be challenging but with vigilance and expert care patients have the best chance of a good clinical outcome.

Cerebral venous thrombosis in patients with autoimmune disease, hematonosis or coronavirus disease 2019: Many familiar faces and some strangers

BACKGROUND

Cerebral venous thrombosis, a rare stroke, is characterized by neurological dysfunction caused by bleeding and/or infarction resulting from venous sinus thrombosis, the so-called venous stroke. Current guidelines recommend anticoagulants as first-line therapy in the treatment of venous stroke. With complicated causes of cerebral venous thrombosis, treatment is difficult, especially when combined with autoimmune diseases, blood diseases, and even COVID-19.

AIMS

This review summarizes the pathophysiological mechanisms, epidemiology, diagnosis, treatment, and clinical prognosis of cerebral venous thrombosis combined with autoimmune diseases, blood diseases, or infectious diseases such as COVID-19.

CONCLUSION

A systematic understanding of particular risk factors that should not be neglected when unconventional cerebral venous thrombosis occurs and for a scientific understanding of pathophysiological mechanisms, clinical diagnosis, and treatment, thus contributing to knowledge on special types of venous stroke.

Diagnosis and Management of Cerebral Venous Thrombosis Due to Polycythemia Vera and Genetic Thrombophilia: Case Report and Literature Review

(1) Background: Cerebral venous and dural sinus thrombosis (CVT) rarely appears in the adult population. It is difficult to diagnosis because of its variable clinical presentation and the overlapping signal intensities of thrombosis and venous flow on conventional MR images and MR venograms. (2) Case presentation: A 41-year-old male patient presented with an acute isolated intracranial hypertension syndrome. The diagnosis of acute thrombosis of the left lateral sinus (both transverse and sigmoid portions), the torcular Herophili, and the bulb of the left internal jugular vein was established by neuroimaging data from head-computed tomography, magnetic resonance imaging (including Contrast-enhanced 3D T1-MPRAGE sequence), and magnetic resonance venography (2D-TOF MR venography). We detected different risk factors (polycythemia vera-PV with JAK2 V617F mutation and inherited low-risk thrombophilia). He was successfully treated with low-molecular-weight heparin, followed by oral anticoagulation. (3) Conclusions: In the case of our patient, polycythemia vera represented a predisposing risk factor for CVT, and the identification of JAK2 V617F mutation was mandatory for the etiology of the disease. Contrast-enhanced 3D T1-MPRAGE sequence proved superior to 2D-TOF MR venography and to conventional SE MR imaging in the diagnosis of acute intracranial dural sinus thrombosis.

Pathological and genomic features of myeloproliferative neoplasms associated with splanchnic vein thrombosis in a single-center cohort

Here, we reviewed clinical-morphological data and investigated mutational profiles by NGS in a single-center series of 58 consecutive MPN-SVT patients admitted to our hospital between January 1979 and November 2021. We identified 15.5% of PV, 13.8% of ET, 34.5% of PMF, 8.6% of SMF and 27.6% of MPN-U. Most cases (84.5%) carried JAK2V617F mutation, while seven patients were characterized by other molecular markers, namely MPL in four and CALR mutations in three cases. NGS was performed in 54 (93.1%) cases: the most frequent additional mutations were found in TET2 (27.8%) and DNMT3A (16.7%) genes, whereas 25 (46.3%) patients had no additional mutation. Cases with JAK2V617F homozygosity had a higher median number of additional mutations than those with low allele burden. More importantly, all cases of leukemic evolution were characterized by a higher median number of co-mutations, and a co-mutational pattern of high-risk lesions, such as truncating mutations of ASXL1, bi-allelic TP53 loss, and CSMD1 mutations. Nevertheless, no difference was found between cases with and without additional somatic mutations regarding fibrotic progression, SVT recurrence, other thrombo-hemorrhagic complications, or death. After a median follow-up of 7.1 years, ten deaths were recorded; fibrotic progression/leukemic evolution was ascertained in one (1.7%) and six (10.3%) patients, respectively, while 22 (37.9%) patients suffered from recurrent thrombosis. In conclusion, our data underline the importance of using NGS analysis in the management of MPN-related SVT as it can support the MPN diagnosis, particularly in "triple-negative" cases, and provide additional information with potential consequences on prognosis and therapeutic strategies.

Prediction of thrombosis in post-polycythemia vera and post-essential thrombocythemia myelofibrosis: a study on 1258 patients

Patients with Philadelphia-negative myeloproliferative neoplasms are at high risk of thrombotic events (TEs). Predisposing factors have been identified in essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (primary MF, PMF), while yet not recognized in post PV/ET-MF (known as secondary MF, SMF). Within the 1258 SMF of the MYSEC (MYelofibrosis SECondary to PV and ET) dataset, 135 (10.7%) developed a TE at a median follow-up of 3.5 years (range, 1-21.4), with an incidence of 2.3% patients per year. Venous events accounted for two-thirds of the total. Cox multivariable analysis, supported by Fine-Gray models with death as competitive risk, showed that being on cytoreductive therapy at time of SMF evolution is associated with an absolute risk reduction of thrombosis equal to 3.3% within 3 years. Considering individually cytoreductive therapies, univariate regression model found that both conventional cytoreduction, mainly hydroxyurea, (HR 0.41, 95% CI: 0.26-0.65, p = 0.0001) and JAK inhibitors, mostly ruxolitinib, (HR 0.50, 95% CI: 0.24-1.02, p = 0.05) were associated with fewer thrombosis. Our study informs treating physicians of a non-low incidence of TEs in post PV/ET-MF and of the potential protective role of cytoreductive therapy in terms of thrombotic events.

Polycythemia vera presenting with pulmonary embolism and splenic infarction: a case report

Pulmonary embolism and splenic infarction are rare in patients with polycythemia vera. We herein describe a man in his early 60s whose main symptoms were chest tightness, cough, and sputum expectoration. Antibiotics, bronchodilators, and mucoactive agents did not improve his symptoms. Pulmonary artery computed tomography angiography showed pulmonary embolism, and abdominal computed tomography showed multiple hypodense foci in the spleen. Bone marrow aspiration cytology, biopsy, and genetic testing confirmed polycythemia vera. The patient’s symptoms were relieved after treatment with hydroxyurea and rivaroxaban. This case emphasizes that although pulmonary embolism and splenic infarction are relatively rare in patients with polycythemia vera, the possibility of polycythemia vera should be considered in clinical practice.

Cerebral venous thrombosis and myeloproliferative neoplasms: A three-center study of 74 consecutive cases

The recent association of cerebral venous thrombosis (CVT) with COVID‐19 vaccinations prompted the current retrospective review of 74 cases of CVT (median age = 44 years, range 15–85; 61% females) associated with myeloproliferative neoplasms (MPNs), seen at the Mayo Clinic, Catholic University of Rome, and University of Florence, between 1991 and 2021. Disease‐specific frequencies were 1.3% (39/2893), 1.2% (21/1811) and 0.2% (3/1888) for essential thrombocythemia, polycythemia vera and primary myelofibrosis, respectively. Cerebral venous thrombosis occurred either prior to (n = 20, 27%), at (n = 32, 44%) or after (n = 22) MPN diagnosis. A total of 72% of patients presented with headaches. Transverse (51%), sagittal (43%) and sigmoid sinuses (35%) were involved with central nervous system hemorrhage noted in 10 (14%) patients. In all, 91% of tested patients harbored JAK2V617F. An underlying thrombophilic condition was identified in 19 (31%) cases and history of thrombosis in 10 (14%). Treatment for CVT included systemic anticoagulation alone (n = 27) or in conjunction with aspirin (n = 24), cytoreductive therapy (n = 14), or both (n = 9). At a median follow‐up of 5.1 years (range 0.1–28.6), recurrent CVT was documented in three (4%) patients while recurrent arterial and venous thromboses and major hemorrhage were recorded in 11%, 9% and 14%, respectively. Follow‐up neurological assessment revealed headaches (n = 9), vision loss (n = 1) and cognitive impairment (n = 1). The current study lends clarity to MPN‐associated CVT and highlights its close association with JAK2V617F, younger age and female gender. Clinical features that distinguish COVID vaccine‐related CVT from MPN‐associated CVT include, in the latter, lower likelihood of concurrent venous thromboses and intracerebral hemorrhage; as a result, MPN‐associated CVT was not fatal.

Prevention of venous thromboembolism in hematologic neoplasms: an expert consensus from SEHH-SETH

Venous thromboembolism (VTE) is a serious complication in hematologic neoplasms, so finding adequate prevention strategies is an urgent requirement. However, prospective studies with large enough cohorts are scarce, limiting the development of evidence-based thromboprophylaxis guidelines. The present position paper is addressed to all hematologists treating patients affected by hematologic neoplasms with the aim to provide clinicians with a useful tool for the prevention of VTE.

Philadelphia chromosome-negative myeloproliferative neoplasms in younger adults: A critical discussion of unmet medical needs, with a focus on pregnancy

Myeloproliferative neoplasms (MPN) are traditionally regarded as a disease of older adults, though a not negligible fraction of cases occurs at a younger age, including women of childbearing potential. MPN in younger patients, indeed, offer several challenges for the clinical hematologist, that goes from difficulties in reaching a timely and accurate diagnosis to a peculiar thrombotic risk, with a relatively high incidence of thromboses in unusual sites (as the splanchnic veins or the cerebral ones). Moreover, the issue of pregnancy is recently gaining more attention as maternal age is rising and molecular screening are widely implemented, leading to a better recognition of these cases, both before and during pregnancy. In the present work we aim at discussing four clinical topic that we identified as areas of uncertainty or true unmet medical needs in the management of younger patients with MPN, with a particular focus on the topic of pregnancy. For each of these topics, we critically reviewed the available evidence that support treatment decisions, though acknowledging that recommendations in this field are mostly based on expert opinion or derived from guidelines of other clinical conditions that share with MPN a high vascular risk, as antiphospholipid syndrome. Taking into consideration both the lack of evidence-based data and the clinical heterogeneity of MPN, we support an individualized strategy of counseling and management for both young patients and for expectant mother with MPN.

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs): A continuum of different disease entities

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell-derived disorders characterized by uncontrolled proliferation of differentiated myeloid cells and close pathobiologic and clinical features. According to the 2016 World Health Organization (WHO) classification, MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision aimed in particular at strengthening the distinction between masked PV and JAK2-mutated ET, and between prefibrotic/early (pre-PMF) and overt PMF. Clinical manifestations in MPNs include constitutional symptoms, microvascular disorders, thrombosis and bleeding, splenomegaly secondary to extramedullary hematopoiesis, cytopenia-related symptoms, and progression to overt MF and acute leukemia. A dysregulation of the JAK/STAT pathway is the unifying mechanistic hallmark of MPNs, and is guided by somatic mutations in driver genes including JAK2, CALR and MPL. Additional mutations in myeloid neoplasm-associated genes have been also identified, with established prognostic relevance, particularly in PMF. Prognostication of MPN patients relies on disease-specific clinical models. The increasing knowledge of MPN biology led to the development of integrated clinical and molecular prognostic scores that allow a more refined stratification. Recently, the therapeutic landscape of MPNs has been revolutionized by the introduction of potent, selective JAK inhibitors (ruxolitinib, fedratinib), that proved effective in controlling disease-related symptoms and splenomegaly, yet leaving unmet critical needs, owing the lack of disease-modifying activity. In this review, we will deal with molecular, clinical, and therapeutic aspects of the three classical MPNs aiming at highlighting either shared characteristics, that overall define a continuum within a single disease family, and uniqueness, at the same time.

Cerebellar venous thrombosis mimicking a cerebellar tumor due to polycythemia vera: a case report

Background

Cerebral venous thrombosis (CVT) occurs rarely in the general population and is frequently associated with confused clinical findings and delayed diagnosis. Isolated cerebellar cortical vein thrombosis is a very rare phenomenon.

Case presentation

This report describes a case with CVT, which is manifested as space-occupying lesions of the cerebellar hemisphere and mimics a cerebellar tumor at the beginning. The diagnosis of CVT was finalized given the laboratory and brain biopsy findings. The etiology may be related to polycythemia vera with Janus Kinase 2 V617F mutation.

Conclusion

Isolated cerebellar vein thrombosis should be considered when swelling and enhancing cerebellar lesions are detected. Polycythemia vera, especially with a positive JAK2 V617F mutation, may be a rare risk factor for CVT.

A systematic review of antithrombotic treatment of venous thromboembolism in patients with myeloproliferative neoplasms

Patients with myeloproliferative neoplasms (MPNs), polycythemia vera, essential thrombocythemia, and primary myelofibrosis, have an increased risk of thrombosis. Risk of recurrent thrombosis can be reduced with antithrombotic therapy and/or cytoreduction, but the optimal long-term management in patients with MPN with a history of venous thromboembolism (VTE) is unknown, and clinical practice is heterogeneous. We performed a systematic review and meta-analysis of randomized trials and observational studies evaluating anticoagulant and/or antiplatelet therapy, with or without cytoreduction, in MPN patients with a history of VTE. A total of 5675 unique citations were screened for eligibility. No randomized trials were identified. Ten observational studies involving 1295 patients with MPN were included in the analysis. Overall, 23% had an arterial or recurrent venous thrombotic event on follow-up. The recurrence risk was lowest for patients on oral anticoagulation plus cytoreduction (16%); 55 of 313 (18%) with vitamin K antagonists (VKA) and 5 of 63 (8%) with direct oral anticoagulants (DOACs). In 746 analyzed patients, the risk of recurrent VTE ranged up to 33% (median 13%) and was low in 63 DOAC plus cytoreduction-treated patients (3.2%). All types of antithrombotic treatments were associated with a lower risk of recurrent VTE when combined with cytoreduction. Most studies had a high risk of bias, whereas clinical and statistical heterogeneity led to inconsistent and imprecise findings. In summary, evidence on the optimal antithrombotic treatment of VTE in patients with MPN is based on observational studies only with low certainty for all strategies. Our data suggest that a combination of anticoagulation and cytoreduction may provide the lowest recurrence risk.

Prevention of recurrent thromboembolism in myeloproliferative neoplasms: review of literature and focus on direct oral anticoagulants

Myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF) are stem cell clonal neoplasms characterized by expansion of late myeloid cells. Thrombosis risk is elevated in MPNs and contributes significantly to morbidity and mortality. Current consensus guidelines make no specific recommendations regarding anticoagulant choice for the treatment of venous thromboembolism (VTE) in MPNs, with most evidence supporting the use of vitamin K antagonists (VKAs) for secondary prophylaxis. However, direct oral anticoagulants (DOACs) are now increasingly being used, although with limited data on safety and efficacy in MPNs specifically. The widespread adoption of DOACs is based on new, high-quality evidence demonstrating safety and efficacy of DOAC treatment for cancer-associated VTE. However, these studies include few if any MPN patients, and MPNs have disease-specific considerations that may elevate thrombosis and bleeding risk. The purpose of this review is to discuss evidence behind current treatment recommendations for thrombosis in MPNs, with special attention to the use of DOACs.

Emerging Role of Neutrophils in the Thrombosis of Chronic Myeloproliferative Neoplasms

Thrombosis is a major cause of morbimortality in patients with chronic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN). In the last decade, multiple lines of evidence support the role of leukocytes in thrombosis of MPN patients. Besides the increase in the number of cells, neutrophils and monocytes of MPN patients show a pro-coagulant activated phenotype. Once activated, neutrophils release structures composed of DNA, histones, and granular proteins, called extracellular neutrophil traps (NETs), which in addition to killing pathogens, provide an ideal matrix for platelet activation and coagulation mechanisms. Herein, we review the published literature related to the involvement of NETs in the pathogenesis of thrombosis in the setting of MPN; the effect that cytoreductive therapies and JAK inhibitors can have on markers of NETosis, and, finally, the novel therapeutic strategies targeting NETs to reduce the thrombotic complications in these patients.

The Essential Thrombocythemia in 2020: What We Know and Where We Still Have to Dig Deep

The Essential Thrombocythemia is a Chronic Philadelphia-negative Myeloproliferative Neoplasm characterized by a survival curve that is only slightly worse than that of age- and sex-adjusted healthy population. The criteria for diagnosis were reviewed in 2016 by WHO. The incidence varies from 0.2 to 2.5:100 000 people per year, with a prevalence of 38 to 57 cases per 100 000 people. The main characteristics of ET are the marked thrombocytosis and the high frequency of thrombosis. The spectrum of symptoms is quite wide, but fatigue results to be the most frequent. Thrombosis is frequently observed, often occurring before or at the time of diagnosis. The classification of thrombotic risk has undergone several revisions. Recently, the revised-IPSET-t has distinguished 4 risk classes, from very low risk to high risk. Driver mutations seem to influence thrombotic risk and prognosis, while the role of sub-driver mutations still remains uncertain. Antiplatelet therapy is recommended in all patients aged ⩾ 60 years and in those with a positive history of thrombosis or with cardiovascular risk factors, while cytoreductive therapy with hydroxyurea or interferon is reserved for high-risk patients.

Optimized and Personalized Phlebotomy Schedules for Patients Suffering From Polycythemia Vera

Polycythemia vera (PV) is a slow-growing type of blood cancer, where the production of red blood cells (RBCs) increase considerably. The principal treatment for targeting the symptoms of PV is bloodletting (phlebotomy) at regular intervals based on data derived from blood counts and physician assessments based on experience. Model-based decision support can help to identify optimal and individualized phlebotomy schedules to improve the treatment success and reduce the number of phlebotomies and thus negative side effects of the therapy. We present an extension of a simple compartment model of the production of RBCs in adults to capture patients suffering from PV. We analyze the model's properties to show the plausibility of its assumptions. We complement this with numerical results using exemplary PV patient data. The model is then used to simulate the dynamics of the disease and to compute optimal treatment plans. We discuss heuristics and solution approaches for different settings, which include constraints arising in real-world applications, where the scheduling of phlebotomies depends on appointments between patients and treating physicians. We expect that this research can support personalized clinical decisions in cases of PV.

From Budd-Chiari syndrome to acquired von Willebrand syndrome: thrombosis and bleeding complications in the myeloproliferative neoplasms

Thrombotic and hemorrhagic complications are prevalent in patients with essential thrombocythemia, polycythemia vera, and myelofibrosis. Given the impact on morbidity and mortality, reducing the risk of thrombosis and/or hemorrhage is a major therapeutic goal. Historically, patients have been risk stratified on the basis of traditional factors, such as advanced age and thrombosis history. However, multiple factors contribute to the thrombotic tendency, including gender, mutational profile, inflammatory stress, and abnormal cell adhesion. Management includes cardiovascular risk reduction and use of antiplatelet therapy, depending on myeloproliferative neoplasm subtype and mutational status. Anticoagulation is a mainstay of therapy for those with venous thrombosis, but practice patterns remain heterogeneous. Cytoreduction is indicated for higher-risk patients, but efficacy may depend on the involved vascular bed. Management of special situations, such as unusual site thrombosis, bleeding, the perioperative period, and pregnancy, are especially challenging. In this article, risk factors and treatment strategies for myeloproliferative neoplasm thrombosis and bleeding, including special situations, are reviewed. Insights gained from recent studies may lead to the development of a more precise risk classification and tailored therapy.

Cerebral and Splanchnic Vein Thrombosis: Advances, Challenges, and Unanswered Questions

Cerebral vein thrombosis (CVT) and splanchnic vein thrombosis (SVT) are two manifestations of venous thromboembolism (VTE) at unusual sites. They have an incidence at least 25-50 times lower than usual site VTE, but represent true clinical challenges. Recent evidence on the epidemiology, risk factors, prognosis, and treatment of CVT and SVT has been published in the last two decades, thus contributing to a better understanding of these diseases. The improvement in imaging techniques and a higher degree of clinical suspicion may have led to the observed increased frequency, whereas a better knowledge of provoking mechanisms could have contributed to reducing the proportion of events classified as unprovoked or idiopathic (13%-21% of CVT, 15%-27% of SVT). Few small randomized clinical trials and a number of observational studies, although hampered by heterogeneous therapeutic approaches, shed light on the safety and effectiveness of anticoagulant therapy in these populations. However, there are still some grey areas that warrant future research. In this narrative review, we discuss recent advances and therapeutic challenges in CVT and SVT.

[Thrombosis and platelet dysfunction in myeloproliferative neoplasms]

Myeloproliferative neoplasms are acquired hematological malignancies, mainly affecting the adult and whose morbidity and mortality stems from haemostasis disorders. The most frequently encountered complications include thrombosis, affecting preferentially the arterial territory, but also atypical locations such as splanchnic vein thrombosis. The pathophysiology of these thromboses is complex and involves different actors: blood cells, endothelium and flow conditions. Numerous studies have been conducted to identify risk factors for thrombosis. To date, only two risk factors have been validated through prospective studies (age over 60 years old, history of thrombotic events) and allow classification of patients as "low risk" and "high risk" as the basis for current treatment recommendations. Haemorrhagic manifestations, less frequent than thrombosis, are mainly related to an alteration of primary haemostasis and are therefore manifested by mucocutaneous bleeding. In these patients, platelet dysfunctions and/or acquired Willebrand syndromes can be found. The pathophysiology of thrombosis and platelet dysfunction during myeloproliferative neoplasms remains to date partially unknown. In this review, we offer to focus on physiopathological mechanisms as well as the latest advances in their understanding.

From Budd-Chiari syndrome to acquired von Willebrand syndrome: thrombosis and bleeding complications in the myeloproliferative neoplasms

Thrombotic and hemorrhagic complications are prevalent in patients with essential thrombocythemia, polycythemia vera, and myelofibrosis. Given the impact on morbidity and mortality, reducing the risk of thrombosis and/or hemorrhage is a major therapeutic goal. Historically, patients have been risk stratified on the basis of traditional factors, such as advanced age and thrombosis history. However, multiple factors contribute to the thrombotic tendency, including gender, mutational profile, inflammatory stress, and abnormal cell adhesion. Management includes cardiovascular risk reduction and use of antiplatelet therapy, depending on myeloproliferative neoplasm subtype and mutational status. Anticoagulation is a mainstay of therapy for those with venous thrombosis, but practice patterns remain heterogeneous. Cytoreduction is indicated for higher-risk patients, but efficacy may depend on the involved vascular bed. Management of special situations, such as unusual site thrombosis, bleeding, the perioperative period, and pregnancy, are especially challenging. In this article, risk factors and treatment strategies for myeloproliferative neoplasm thrombosis and bleeding, including special situations, are reviewed. Insights gained from recent studies may lead to the development of a more precise risk classification and tailored therapy.

Developments in diagnosis and treatment of essential thrombocythemia

INTRODUCTION

Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by thrombocytosis, increased risk of thrombotic/hemorrhagic events and clonal evolution into blast phase or myelofibrosis. Areas covered: The authors will discuss biology, diagnosis, prognosis, therapy, and outcome of ET. An accurate molecular-morphologic assessment is necessary in order to properly establish diagnosis and prognosis of ET. Stratification for thrombosis prediction is essential, and IPSET-t model is widely applied. The current treatment strategy is directed to lower the rate of vascular events using cytoreduction in patients at high risk. Prophylactic low dose aspirin indication is more uncertain. To date, therapies for patients who are resistant or intolerant to first-line treatments are scarce. Overall, life expectancy indicates an indolent disease, but IPSET model helps in predicting survival at the time of diagnosis. Expert opinion: Challenging for the future will be to share criteria for ET diagnosis with the community. New insights into the molecular pathogenesis of the disease will improve the prediction of clonal evolution and outcome, and lead to the use of disease-modifying treatments.

Cerebral venous sinus thrombosis

The cerebral venous system is an unusual site of thrombosis, with a particularly high incidence in young adults. This incidence has increased in past decades because of the improvement of neuroradiological techniques. Risk factors for cerebral venous sinus thrombosis overlap with those of other venous thromboembolism sites; however, some are specific for this particular anatomical district. Prognosis is favorable in most cases if diagnosis is made rapidly and treatment is promptly initiated, even if acute complications or chronic invalidity still occur in a quarter of patients. The mainstay of treatment is anticoagulation, which is necessary in order to block clot propagation and obtain recanalization. Intracranial bleeding does not contraindicate anticoagulation. Endovascular procedures are reserved for patients with a particularly severe presentation or rapidly declining neurological symptoms despite appropriate anticoagulation, although data from clinical trials are lacking. Specifically, this review addresses the epidemiology, clinical presentation and course, risk factors, and treatment of cerebral venous sinus thrombosis, with a special focus on the pediatric population.

Approach to thrombosis at unusual sites: Splanchnic and cerebral vein thrombosis

Splanchnic vein thrombosis (SVT) and cerebral vein thrombosis (CVT) are two manifestations of unusual site venous thromboembolism (VTE). SVT includes thrombosis in the portal, mesenteric or splenic veins, and the Budd-Chiari syndrome. CVT encompasses thrombosis of the dural venous sinuses and thrombosis of the cerebral veins. Unusual site VTE often represents a diagnostic and therapeutic challenge because of the heterogeneity in clinical presentation, the limited evidence available in the literature on the acute and long-term prognosis of these diseases, and the lack of large randomized controlled trials evaluating different treatment options. This narrative review describes the approach to patients with SVT or CVT by examining the diagnostic process, the assessment of potential risk factors and the appropriate anticoagulant treatment.

Management of venous thromboembolism in myeloproliferative neoplasms

PURPOSE OF REVIEW

Venous thromboembolism is frequent in chronic myeloproliferative neoplasms (MPN). The current strategy for its management includes cytoreductive therapy and antithrombotic prophylaxis, but many issues remain uncertain. In this review, the risk factors and prevention of recurrences will be discussed.

RECENT FINDINGS

Around one-third of patients with polycythemia vera and essential thrombocythemia experience a major thrombosis at diagnosis or during follow-up. According to the European Leukemia Net guidelines, these patients must be included in the high-risk group for thrombotic recurrence and should be treated with cytoreduction and antiplatelet or anticoagulant drugs in the presence of arterial or venous thrombosis, respectively. Despite this treatment, the annual incidence of recurrence after the first venous thrombosis varies from 4.2 to 6.5% on vitamin K-antagonists and is doubled after discontinuation. The highest incidence of recurrence occurs after cerebral and hepatic vein thrombosis (8.8 and 8 per 100 pt-years, respectively). The occurrence of major bleeding on vitamin K-antagonists is similar to a non-MPN population and accounts for a rate of 1.8-2.4 per 100 pt-years.

SUMMARY

After venous thrombosis, the incidence of recurrence in MPN remains elevated, which suggested there was a need to review the current recommendations of primary and secondary prophylaxis.

Should We Screen for Janus Kinase 2 V617F Mutation in Cerebral Venous Thrombosis?

BACKGROUND

The presence of Janus Kinase 2 (JAK2) V617F mutation represents a major diagnostic criterion for detecting myeloproliferative neoplasms (MPN) and even in the absence of overt MPN, JAK2 V617F mutation is associated with splanchnic vein thrombosis. However, the actual prevalence and diagnostic value of the JAK2 V617F mutation in patients with cerebral venous thrombosis (CVT) are not known. The aims of this study were to assess the prevalence of JAK2 V617F mutation in a large group of consecutive CVT patients, to detect clinical, biological, and radiological features associated with the mutation, and to determine the long-term venous thrombosis recurrence rate in CVT patients with JAK2 mutation but without overt MPN in order to recommend the best preventive treatment.

METHODS

This was a prospective study conducted on consecutive patients with a first-ever radiologically confirmed CVT. JAK2 V617F mutation analysis was assessed in all the study subjects. JAK2 V617F-positive patients were followed up to detect new venous thrombotic events.

RESULTS

Of the 125 included subjects, 7 were found to have JAK2 V617F mutation (5.6%; 95% CI 2.3-11.2). Older age (p = 0.039) and higher platelet count (p = 0.004) were independently associated with JAK2 V617F positivity in patients without overt MPN. During a mean follow-up period of 59 (SD 46) months, 2 JAK2 V617F-positive patients presented with 4 new venous thromboembolic events.

CONCLUSIONS

Screening for the JAK2 V617F mutation in CVT patients seems to be useful even in the absence of overt MPN and/or in the presence of other risk factors for CVT because of its relatively high prevalence and the risk of thrombosis recurrence.

Ten years of cerebral venous thrombosis: male gender and myeloproliferative neoplasm is associated with thrombotic recurrence in unprovoked events

Cerebral venous thrombosis (CVT) is a rare venous thrombotic event. We review our local experience in the management of CVT in comparison to other venous thromboembolism (VTE) with specific focus on risk factors for thrombotic recurrence. Retrospective evaluation of consecutive CVT presentations from January 2005 to June 2015, at two major tertiary hospitals in Northeast Melbourne, Australia. This population was compared to a separate audit of 1003 consecutive patients with DVT and PE. Fifty-two patients (30 female, 22 male) with a median age of 40 (18-83) years, presented with 53 episodes of CVT. Twenty-nine episodes (55 %) were associated with an underlying risk factor, with hormonal risk factors in females being most common. The median duration of anticoagulation was 6 months with 11 receiving life-long anticoagulation. Eighty-one percent had residual thrombosis on repeat imaging, which was not associated with recurrence at the same or distant site. Nine (17 %) had CVT-related haemorrhagic transformation with two resultant CVT-related deaths (RR 22.5; p = 0.04). All three VTE recurrences occured in males with unprovoked events (RR 18.2; p = 0.05) who were subsequently diagnosed with myeloproliferative neoplasm (MPN). Compared to the non-cancer VTE population, non-cancer CVT patients were younger, had similar rate of provoked events and VTE recurrence, although with significantly higher rate of MPN diagnosis (RR 9.30 (2.29-37.76); p = 0.002) CVT is a rare thrombotic disorder. All recurrences in this audit occurred in male patients with unprovoked events and subsequent diagnosis of MPN, suggesting further evaluation for MPN may be warranted in patients with unprovoked CVT.

Discrepancies between bone marrow histopathology and clinical phenotype in BCR-ABL1-negative myeloproliferative neoplasms associated with splanchnic vein thrombosis

We examined a consecutive series of 29 patients with myeloproliferative neoplasms (MPNs) associated with splanchnic vein thrombosis (SVT) in order to evaluate their bone marrow morphology and identify possible associations between histological findings and clinical features. Eleven patients showed the morphological features of polycythemia vera (PV), 11 of primary myelofibrosis (PMF) and six of essential thrombocythemia (ET). Molecular analyses identified the JAK2 V617F mutation in 27 patients; one of the JAK2-negative patients carried the MPL W515K mutation, the other was "triple-negative" (no JAK2, MPL or CALR mutation). On the basis of the WHO classification, three patients were classified as having PV, 11 as having PMF, and two as having ET; the remaining 13 cases fell into the MPN-unclassifiable category as there were discrepancies between their morphological and clinical features. In conclusion, our findings suggest that bone marrow histology should always be considered a key component of the diagnostic algorithm in patients with SVT, but that it is not enough to distinguish the different entities. This is particularly important because diagnoses of PV, PMF or ET have very different prognoses and obviously imply different therapies. It is therefore necessary to adopt a comprehensive approach that considers morphological, clinical and molecular data.

Cerebral vein thrombosis in patients with Philadelphia-negative myeloproliferative neoplasms. An European Leukemia Net study

To investigate the characteristics and clinical course of cerebral vein thrombosis (CVT) in patients with myeloproliferative neoplasms (MPN) we compared 48 patients with MPN and CVT (group MPN-CVT) to 87 with MPN and other venous thrombosis (group MPN-VT) and 178 with MPN and no thrombosis (group MPN-NoT) matched by sex, age at diagnosis of MPN (±5 years) and type of MPN. The study population was identified among 5,500 patients with MPN, from January 1982 to June 2013. Thrombophilia abnormalities were significantly more prevalent in the MPN-CVT and MPN-VT than in MPN-NoT group (P = 0.015), as well as the JAK2 V617F mutation in patients with essential thrombocythemia (P = 0.059). Compared to MPN-VT, MPN-CVT patients had a higher rate of recurrent thrombosis (42% vs. 25%, P = 0.049) despite a shorter median follow-up period (6.1 vs. 10.3 years, P = 0.019), a higher long-term antithrombotic (94% vs. 84%, P = 0.099) and a similar cytoreductive treatment (79% vs. 70%, P = 0.311). The incidence of recurrent thrombosis was double in MPN-CVT than in MPN-VT group (8.8% and 4.2% patient-years, P = 0.022), and CVT and unprovoked event were the only predictive variables in a multivariate model including also sex, blood count, thrombophilia, cytoreductive, and antithrombotic treatment (HR 1.97, 95%CI 1.05-3.72 and 2.09, 1.09-4.00, respectively).

How I treat polycythemia vera

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm associated with JAK2 mutations (V617F or exon 12) in almost all cases. The World Health Organization has defined the criteria for diagnosis, but it is still unclear which parameter (hemoglobin or hematocrit) is the most reliable for demonstrating increased red cell volume and for monitoring response to therapy; also, the role of bone marrow biopsy is being revisited. PV is associated with reduced survival because of cardiovascular complications and progression to post-PV myelofibrosis or leukemia. Criteria for risk-adapted treatment rely on the likelihood of thrombosis. Controlled trials have demonstrated that incidence of cardiovascular events is reduced by sustained control of hematocrit with phlebotomies (low-risk patients) and/or cytotoxic agents (high-risk patients) and antiplatelet therapy with aspirin. Hydroxyurea and interferon may be used as first-line treatments, whereas busulfan is reserved for patients that are refractory or resistant to first-line agents. However, there is no evidence that therapy improves survival, and the significance of reduction of JAK2 mutated allele burden produced by interferon is unknown. PV is also associated with a plethora of symptoms that are poorly controlled by conventional therapy. This article summarizes my approach to the management of PV in daily clinical practice.