Liver and Vascular Involvement in Philadelphia-Negative Chronic Myeloproliferative Neoplasms—A Narrative Review

Hepatosplenomegaly can occur in extrahepatic diseases such as Philadelphia-negative chronic myeloproliferative neoplasms (MPNs), which may involve the liver and vasculature. In myelofibrosis, extramedullary hematopoiesis can be present in the liver, even within hepatic sinusoids. Liver biopsies in MPN patients have shown platelet aggregates obstructing these sinusoids. Both liver and spleen stiffness are significantly higher in myelofibrosis, correlating with the severity of bone marrow fibrosis. Spleen stiffness is also elevated in myelofibrosis and polycythemia Vera compared to essential thrombocythemia. MPNs are a leading cause of splanchnic vein thrombosis in the absence of cirrhosis or local malignancy, especially in the presence of the JAK2V617F mutation. This mutation promotes thrombosis through endothelial dysfunction and inflammation. It is found in endothelial cells, where it enhances leukocyte adhesion and upregulates thrombogenic and inflammatory genes. Hepatic sinusoidal microthromboses in MPNs may contribute to portal hypertension and liver dysfunction. MPN therapies can also affect liver function. While hepatocytolysis has been reported, agents such as Hydroxycarbamide and Ruxolitinib exhibit antifibrotic hepatic effects in experimental models. Overall, MPNs are linked to chronic inflammation, increased thrombotic risk—particularly splanchnic thrombosis—and atherogenesis.