Thrombosis in myeloproliferative neoplasms: A clinical and pathophysiological perspective

Arterial Thrombosis in Patients with Cancer

Patients with cancer are at increased risk of arterial thromboembolic disease due to the presence of risk factors common to both the development of cancer and arterial thrombosis, the cancer itself, and the treatments provided to treat cancer. We review here the epidemiology and pathophysiology of arterial thromboembolic disease in cancer, along with its prevention and treatment strategies. We also propose a generalized approach for the management of arterial thromboembolic disease in this patient population.

A Review About the Assessment of the Bleeding and Thrombosis Risk for Patients With Myeloproliferative Neoplasms Scheduled for Surgery

Myeloproliferative neoplasms (MPNs) present a unique challenge in surgical management due to their inherent predisposition to both bleeding and thrombosis. MPNs are a heterogenous group of acquired clonal conditions. The three classic MPNs are essential thrombocythemia (ET), myelofibrosis (PMF), and polycythemia vera (PV). All subtypes of MPN are associated with both thrombotic and bleeding complications. There are four risk categories for thrombosis in MPN patients: age, thrombosis history, and JAK-2 mutation. They are further classified as very low, low, intermediate, and high risk. The genetic landscape of MPN is fascinating and complex like all myeloid disorders. Bleeding risk can be assessed through leukocytosis, thrombocytosis, acquired von Willebrand syndrome (AVWS), and a previous history of bleeding in a patient. Risk assessment and perioperative management are important aspects of improving the quality of life and preventing complications in surgeries. Preoperative management includes a risk assessment of venous thromboembolism, use of appropriate pharmacological treatment, platelet count control, and correction and cardiovascular risk factors. This review summarizes the assessment of bleeding and thrombosis risk for patients with MPNs scheduled for surgery. Furthermore, this review discusses various tools that can be used to identify MPN patients at risk of thrombosis prior to surgery.

Splenic infarction secondary to polycythemia Vera: Case report and literature review

Splenic infarction is a medical condition characterized by compromised blood flow to the spleen, resulting in partial or complete organ infarction. This condition is commonly observed in patients with an increased risk of thrombosis, such as those with Polycythemia Vera (PV). A 40-year-old female patient presented with fatigue, weakness, and an enlarged spleen, further tests revealed elevated levels of hemoglobin, white blood cells, and platelets. A bone marrow biopsy and positive Jack II mutations confirmed the diagnosis of PV. The patient later developed portal hypertension, varices, and splenic infarction. This case report aims to raise awareness about the potential complications of PV and emphasizes the importance of early intervention to prevent serious consequences such as splenic infarction. Additionally, it highlights the role of splenectomy in managing complications associated with PV.

Molecular Mechanisms Underlying Vascular Liver Diseases: Focus on Thrombosis

Vascular liver disorders (VLDs) comprise a wide spectrum of clinical-pathological entities that primarily affect the hepatic vascular system of both cirrhotic and non-cirrhotic patients. VLDs more frequently involve the portal and the hepatic veins, as well as liver sinusoids, resulting in an imbalance of liver homeostasis with serious consequences, such as the development of portal hypertension and liver fibrosis. Surprisingly, many VLDs are characterized by a prothrombotic phenotype. The molecular mechanisms that cause thrombosis in VLD are only partially explained by the alteration in the Virchow's triad (hypercoagulability, blood stasis, and endothelial damage) and nowadays their pathogenesis is incompletely described and understood. Studies about this topic have been hampered by the low incidence of VLDs in the general population and by the absence of suitable animal models. Recently, the role of coagulation imbalance in liver disease has been postulated as one of the main mechanisms linked to fibrogenesis, so a novel interest in vascular alterations of the liver has been renewed. This review provides a detailed analysis of the current knowledge of molecular mechanisms of VLD. We also focus on the promising role of anticoagulation as a strategy to prevent liver complications and to improve the outcome of these patients.

Thrombosis Risk Assessment in Myeloproliferative Neoplasm-Is There a Role for Viscoelastic Testing?

Philadelphia chromosome-negative myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia, and myelofibrosis. They are associated with increased thrombotic events, and the primary goal of therapy, in particular those with polycythemia vera and essential thrombocythemia, is the prevention of thrombotic complications typically with antiplatelet therapy and/or cytoreduction. While several patient-, disease-, and genomic-related factors have been identified to influence thrombotic risks, there are no routine laboratory investigations to date that are sufficiently accurate to assess the underlying procoagulant state and predict the thrombotic risks. Conventional coagulation testing only measures time to clot formation and cannot reliably predict bleeding and thrombotic risks. Global coagulation assays such as thromboelastography, thrombin, and fibrin generation may provide a more thorough assessment of hemostatic function. Thromboelastography and thromboelastometry are viscoelastic tests which measure the mechanical properties of the hemostatic process, including the global dynamics of clot formation, stabilization, and dissolution. While viscoelastic testing is gaining traction in the investigations of coagulopathies and goal-directed blood product replacement in trauma and massive transfusion settings, the role of these assays in thrombosis is less well defined. Here, we provide a review of the current evidence of the role of viscoelastic testing in myeloproliferative neoplasm, particularly in the thrombotic risk assessment.

Diagnostic and Therapeutic Challenges of Chronic Portal Vein Thrombosis Secondary to Myeloproliferative Neoplasm in Sub-Saharan Region: A Series of Cases and Literature Review

Myeloproliferative neoplasms (MPN) are the commonest causes of non-cirrhotic abdominal vein thrombosis. MPN was observed in 30-40% with Budd Chiari Syndrome (BCS) and portal vein thrombosis (PVT), whereas this is the cause in only a minority of other types of venous thrombosis. Herein, we report 10 cases of chronic PVT secondary to Janus Kinase 2 gene (JAk 2) positive myeloproliferative neoplasm (MPN). The median age was 35 years with M:F 1:1. Portal hypertension was present at presentation in all of them. Nine patients have esophageal varices, of which 6 have bleeding at presentation. Classical MPN phenotype on complete blood count (CBC) was not present in 6 of them. Management of patients with anticoagulation was difficult with 4 patients experiencing bleeding during anticoagulation, and bleeding occurring despite the target international normalized ratio (INR) in 2 of them. Portal hypertension leading to hypersplenism and hemodilution may mask erythrocytosis and thrombocytosis, which are the main criteria used to diagnose MPN. The resulting absence of a typical MPN phenotype in routine laboratory studies alongside accessibility issues, and the need for a multidisciplinary treatment approach imparts a diagnostic as well as a therapeutic challenge for chronic PVT associated with Jak 2 positive MPN in sub-Saharan patients.

Molecular Genetics of Thrombotic Myeloproliferative Neoplasms: Implications in Precision Oncology

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) include polycythaemia vera, essential thrombocythaemia, and primary myelofibrosis. Unlike monogenic disorders, a more complicated series of genetic mutations are believed to be responsible for MPN with various degrees of thromboembolic and bleeding complications. Thrombosis is one of the early manifestations in patients with MPN. To date, the driver genes responsible for MPN include JAK2, CALR, MPL, TET2, ASXL1, and MTHFR. Affords have been done to elucidate these mutations and the incidence of thromboembolic events. Several lines of evidence indicate that mutations in JAK2, MPL, TET2 and ASXL1 gene and polymorphisms in several clotting factors (GPIa, GPIIa, and GPIIIa) are associated with the occurrence and prevalence of thrombosis in MPN patients. Some polymorphisms within XRCC1, FBG, F2, F5, F7, F12, MMP9, HPA5, MTHFR, SDF-1, FAS, FASL, TERT, ACE, and TLR4 genes may also play a role in MPN manifestation. This review aims to provide an insightful overview on the genetic perspective of thrombotic complications in patients with MPN.

JAK2V617F mutation and circulating extracellular vesicles in essential thrombocythemia

The clinical course of essential thrombocythemia (ET) is complicated with thrombosis which significantly impacts patients' mortality. Studies have identified JAK2V617F mutation as an independent risk factor for thrombosis. Circulating extracellular vesicles (EVs) were evaluated in several studies regarding myeloproliferative neoplasms and thrombosis as potential biomarkers. The present study investigates the relationship between JAK2V617F mutation and EVs levels in 119 ET patients. Our analyses revealed that JAK2V617F-positive patients are at a significantly increased risk of thrombosis within five years before the ET diagnosis (hazard ratio [95% CI]: 11.9 [1.7-83.7], P = 0.013), and that JAK2V617F mutation is an independent risk factor for thrombosis at ET diagnosis or during the follow-up (hazard ratio [95% CI]: 3.56 [1.47-8.62], P = 0.005). ET patients have higher levels of platelet-EVs, erythrocyte-EVs and procoagulant activity of EVs than the healthy population. Absolute and relative counts of platelet-EVs are increased in the presence of JAK2V617F mutation (P = 0.018, P = 0.024, respectively). In conclusion, our results support the role of JAK2V617F mutation in the pathogenesis of thrombosis in essential thrombocythemia through enhancing platelet activation.