Portal hypertension without cirrhosis of the liver has been described in several hematological conditions.1-15 Though there may be thrombosis of the portal, splenic, or hepatic veins in cases of the myeloproliferative syndromes,13-15 many cases have been described in which these veins were patent.1-8,13 The etiology of portal hypertension in these patients with patent venous systems has not been clearly elucidated. Alternative explanations include increased portal flow secondary to splenomegaly, the "forward flow" theory,2,3,8 and increased hepatic resistance from infiltrative lesions in portal tracts and sinusoids.7,13
Portal hypertension without cirrhosis also occurs in tropical splenomegaly16 and systemic-portal arteriovenous fistulae.17,18 Investigations in these patients have also suggested that increased portal blood flow may cause portal hypertension in the absence of cirrhosis.16,17
The case described here represents an example of hematological portal hypertension. Bone marrow obliteration led to hepatosplenomegaly from extramedullary hematopoesis. Portal hypertension became obvious when a large epigastric collateral vein appeared.