Agnogenic Myeloid Metaplasia, Portal Hypertension, and Sinusoidal Abnormalities

Portal hypertension secondary to myelofibrosis with myeloid metaplasia: A study of 13 cases

“…The first theory states that PH develops in MMM patients due to sinusoidal narrowing and intrahepatic obstruction caused by extramedullary hematopoiesis and infiltration of the liver by myeloid cells leading to increased intrahepatic resistance [6,16,17] , while the other theory states that PH develops in such patients due to increased portal blood flow through the enlarged spleen [8,18,19] . Portal vein thrombosis is a major cause of PH in hematological disorders [6,16,18] . It is still unclear whether portal vein thrombosis in MMM is caused by a hypercoagulable state and hyperviscosity related to underlying disease or as a consequence of stasis due to elevated sinusoidal pressure.…”

“…However, one of these patients had a very high white blood cell count (49 000 cells/mL), possibly contributing to thrombosis by increasing the blood viscosity. When thrombosis is absent, PH has been related to an increased intrahepatic resistance and sinusoidal narrowing due to the myeloid metaplasia [6,16,17] and/or due to a marked increase in portal flow as a consequence of marked splenomegaly [8,18,19] . In our report, the 10 patients who did not have portal vein thrombosis had splenomegaly; six of them had dilated splenic veins with increased portal blood flow indicated by abdominal doppler ultrasound.…”

“…The typical clinical features include hypermetabolic symptoms (fever, fatigue and weight loss), marked splenomegaly and anemia [3] . PH with subsequent ascites and gastrointestinal hemorrhage from ruptured varices has been described in patients with MMM [4][5][6][7][8] . Only a few published studies have discussed this issue extensively.…”

Transjugular Intrahepatic Portosystemic Shunt for the Treatment of Portal Hypertension Due to Idiopathic Myelofibrosis

“…The sinusoidal fibrosis may have been due to a reaction for an increased hepatic blood flow and extramedullary hematopoiesis in the liver (3)(4)(5). On the other hand, liver cirrhosis demonstrates chronic progressive fibrosis of the liver, and the area of fibrosis is the hepatocytes (7).…”

“…Platelets and megakaryocytes contain large amounts of growth factors, including platelet-derived growth factor and transforming growth factor beta, which have both been shown to stimulate the proliferation of fibroblasts (3,8). Platelets and megakaryocytes in the space of Disse in the liver ultrastructurally contain extramedullary hematopoiesis (3,9 (10,11).…”