Bleeding Complications in JAK2-Variant Essential Thrombocythemia: A Revisit in 2025.

Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterised by sustained thrombocytosis. Paradoxically, bleeding complications remain an under-recognised clinical challenge. Compared with CALR-mutated patients, those harbouring the JAK2-V617F variant appear more prone to haemorrhage. This may be secondary to acquired von Willebrand syndrome (AvWS) and intrinsic platelet dysfunction. AvWS in ET arises from extreme platelet counts driving the adsorption and proteolysis of high-molecular-weight von Willebrand factor (VWF) multimers, producing a qualitative VWF defect akin to type 2A von Willebrand disease. However, the platelet count threshold for AvWS is variable, and patients with platelet counts below 1000 × 10/L may still exhibit clinically significant VWF anomalies. Diagnosis relies on tests such as VWF activity and antigen levels. Perioperative management of patients with AvWS focuses on correcting the VWF defect and/or lowering platelet counts. Ultimately, clinicians must balance between preventing thrombosis and bleeding by tailoring management to each patient. The authors have confirmed clinical trial registration is not needed for this submission.