Editor's Note: Hepatic vascular diseases include lesions in the hepatic artery, portal vein, hepatic vein, and hepatic sinusoids. Due to the lack of specific clinical manifestations, and differences in the types and classifications of vascular involvement, it is often challenging to make rapid and accurate diagnoses in clinical practice. The various anatomical features of hepatic vascular lesions lead to distinct hemodynamic changes, which are reflected in their clinical, imaging, and pathological presentations. Diagnosing these conditions requires spatial thinking and a multi-angle, multi-dimensional approach to improve diagnostic accuracy. Recently, Dr. Bo Feng from Peking University People's Hospital delivered an insightful presentation titled "Classification and Differentiation of Hepatic Vascular Lesions" at the 4th Jincheng Hepatology Forum.

As the largest digestive gland in the body, the liver has a unique dual blood supply, including inflow vessels (hepatic artery and portal vein) and outflow vessels (hepatic veins). The terminal branches of the portal vein within the liver expand into hepatic venous sinusoids, where the terminal branches of the hepatic artery join. Blood from the sinusoids drains through the central vein and sublobular veins into the left, middle, and right hepatic veins. The liver can be divided into two hemilivers and eight segments based on the Glissonian system (branches of the intrahepatic portal vein and hepatic veins). Histologically, it is divided into hepatic lobules and portal areas.

Classification of Hepatic Vascular Lesions

1. Hepatic Arterial Lesions

  1. Congenital Anomalies: Common congenital abnormalities include the transposition of the left and right hepatic arteries, with cases where either a single left or right hepatic artery is present, or the hepatic artery originates from the superior mesenteric artery. While these anomalies are usually clinically insignificant, they are crucial during surgical procedures and angiography.
  2. Hepatic Artery Occlusion: Often caused by thrombosis, embolism, abdominal trauma, or surgical ligation, hepatic artery occlusion can result in ischemic infarction of the liver.
  3. Intrahepatic Arterial Thrombosis: This condition is frequently associated with arteritis of the hepatic artery, affecting approximately 60% of patients with polyarteritis nodosa. It may also result from trauma, liver transplantation, or transhepatic arterial chemotherapy infusion.
  4. Hepatic Artery Aneurysms: Although not uncommon, hepatic artery aneurysms are often cystic and multiple, manifesting as abdominal pain, jaundice, and biliary bleeding. When large enough, they can cause mechanical biliary obstruction. If untreated, 75% of aneurysms rupture, resulting in high mortality. Diagnosis is typically confirmed via contrast-enhanced CT or angiography, and treatment involves arterial embolization or hepatic artery ligation.

2. Portal Venous Lesions

  1. Portal Vein Thrombosis: This condition involves thrombosis in the main trunk of the portal vein and/or its left and right branches, with or without associated mesenteric or splenic vein thrombosis. It can be caused by thrombus, tumor thrombus, or parasitic eggs (e.g., schistosomiasis). Acute portal vein thrombosis lasts less than 6 months, while chronic thrombosis persists for 6 months or more. Based on the degree of occlusion in the portal vein trunk, thrombosis is classified as complete occlusion (no patent lumen), partial occlusion (over 50% of the original lumen obstructed), or mild occlusion (less than 50% obstructed).
  2. Cavernous Transformation of the Portal Vein: This rare vascular lesion occurs when the portal vein becomes obstructed, leading to increased portal venous pressure and the development of a sponge-like collateral circulation around the portal vein.
  3. Regional Portal Hypertension: Also known as left-sided portal hypertension, this condition arises from splenic vein obstruction or stenosis, causing impaired venous return. It is a rare but life-threatening cause of upper gastrointestinal bleeding.
  4. Idiopathic Portal Hypertension: Rare in clinical practice, the etiology is unknown. It manifests with symptoms of portal hypertension but with normal liver function. Pathologically, there is fibrosis and sclerosis of intrahepatic portal veins, with obliteration or destruction of terminal portal vein branches and nodular regenerative hyperplasia. However, there is no cirrhosis.
  5. Portal Sinusoidal Vascular Disease (PSVD): The liver biopsy of PSVD shows pathology consistent with idiopathic portal hypertension, with or without clinical or imaging signs of portal hypertension. Diagnostic criteria include the exclusion of diseases affecting the hepatic veins (e.g., Budd-Chiari syndrome) and confirmation of the absence of cirrhosis. PSVD can be classified into cases with or without portal hypertension symptoms.

3. Sinusoidal and Microvascular Lesions

  1. Sinusoidal Obstruction Syndrome (Veno-Occlusive Disease, VOD): This condition results from endothelial cell injury, leading to microthrombi formation, hepatic congestion, liver damage, and portal hypertension. Common causes include pyrrolizidine alkaloid-containing plants, hematopoietic stem cell transplantation (HSCT), and chemotherapy.
  2. Peliosis Hepatis: A rare benign liver condition characterized by blood-filled cystic spaces within the liver. It may be associated with cytotoxic drugs, radiation, infections, or immunodeficiency.
  3. HSCT-Related Hepatic Thrombotic Microangiopathy (TMA): This severe complication of HSCT presents with microangiopathic hemolytic anemia, thrombocytopenia, and multi-organ dysfunction, including early-onset and late-onset forms of TMA.
  4. Sickle Cell Disease: Sickle cell disease can lead to sinusoidal microthrombosis, causing chronic organ damage due to vascular occlusion and ischemia.

4. Hepatic Vein and Inferior Vena Cava Lesions

  1. Sarcoidosis Involving the Hepatic Veins: Sarcoidosis can lead to hepatic involvement, resulting in portal hypertension due to granulomatous obstruction or fibrosis.
  2. Budd-Chiari Syndrome: This condition is caused by obstruction of the hepatic veins or the inferior vena cava above the hepatic vein outlets, leading to portal hypertension.
  3. Chronic Hepatic Congestion: Commonly seen in congestive heart failure, this condition results in a “nutmeg liver” appearance due to central lobular congestion and fibrosis.

5. Other Hepatic Vascular Diseases

  1. Hepatic Arteriovenous Fistulas: Abnormal connections between the hepatic artery and portal vein can lead to significant complications like portal hypertension.
  2. Hereditary Hemorrhagic Telangiectasia: A rare autosomal dominant disorder characterized by vascular malformations and the potential for life-threatening complications, such as heart failure and portal hypertension.

Differential Diagnosis of Hepatic TMA, GVHD, and SOS

Distinguishing between graft-versus-host disease (GVHD) and TA-TMA can be challenging, requiring clinical and laboratory markers. VOD/SOS is another complication that must be differentiated from TA-TMA, primarily affecting the liver, while TA-TMA often affects the kidneys.

Conclusion

  1. Hepatic vascular diseases are diverse and can affect various parts of the liver vasculature.
  2. Hepatic vascular lesions are important causes of non-cirrhotic portal hypertension.
  3. Early detection, diagnosis, and intervention are essential to prevent disease progression.
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Last updated on 2024.09.13