Cavernous Transformation and Portal Vein Obstruction

Description

• Cavernous transformation
  • Is a term used to describe the collection of collaterals that develop around an obstructed vessel
  • Often develops with obstruction of the portal vein
• Portal vein obstruction
  • Can occur anywhere along the course of the main portal vein or splenic vein, between the hilum of the spleen and the porta hepatis
  • In pediatrics, obstruction is most typically of the portal vein.
  • Major cause of prehepatic or noncirrhotic portal hypertension

Epidemiology

• Most children with portal vein thrombosis present between birth and 15 years of age.
• Acute presentation is rare.
• Chronic cases present with complications of portal hypertension.
• Gastrointestinal (GI) bleeding is more typical in patients presenting <7 years of age.
• Splenomegaly in the absence of symptoms is more typical for patients aged 5 to 15 years.

Risk Factors

Pathophysiology

• In cirrhosis and hepatic malignancies, the thrombus usually begins intrahepatically and spreads to the extrahepatic portal vein.
• In most other etiologies, the thrombus usually starts at the site of origin along the portal vein.
• Occasionally, thrombosis of the splenic vein propagates to the portal vein, most often resulting from an adjacent inflammatory process (e.g., severe pancreatitis).
• Asymptomatic splenomegaly or upper GI hemorrhage results from extrahepatic portal hypertension.
• Less commonly, ascites or failure to thrive can occur, as well as portopulmonary hypertension

Etiology

50% of portal vein obstructions are idiopathic. Identified causes include the following:

• Congenital vascular anomaly
  • Portal vein malformation
  • Webs or diaphragms within the portal vein
• Clot resulting from a hypercoagulable state
• Clot from other causes:
  • Omphalitis
  • Umbilical vein catheterization
  • Portal pyelophlebitis
  • Intra-abdominal sepsis
  • Surgery near the porta hepatis
  • Sepsis
  • Cholangitis
  • Dehydration
  • Trauma
• Other causes for portal vein obstruction in older children:
  • Ascending pyelophlebitis from perforated appendicitis
  • Primary peritonitis, cholangitis, and pancreatitis causing a splenic vein thrombosis
  • Inflammatory bowel disease