A 60-year-old male with a history of HBV exposure, HCV with spontaneous clearance, and myelofibrosis with transfusion-dependent pancytopenia presents with tense ascites and coffee ground emesis. On exam he has massive splenomegaly and a nontender abdomen. Labs are notable for a hemoglobin of 6 gm/dL, platelet count of 12 K/L, INR of 1.2, and normal liver profile. Fluid studies from paracentesis reveal a serum-ascites albumin gradient (SAAG) of 1.8 gm/dL and total protein of 1.7 gm/dL, consistent with portal hypertension. EGD shows multiple columns of non-bleeding large esophageal varices with stigmata of recent bleeding, gastric varices, and portal hypertensive gastropathy. A transjugular liver biopsy with pressure measurement shows a hepatic venous pressure gradient (HVPG) of 10 mmHg. Pathology reveals minimal fibrosis, CD34+ cells within the sinusoids, and reticulin stain shows diffuse nodules surrounded by a compressed reticulin network.
In addition to extramedullary hematopoiesis due to myelofibrosis and increased portal flow, what other entity is contributing to this patient’s portal hypertension?