Banti syndrome: Year of the Zebra 2026

Banti syndrome, also known as idiopathic non-cirrhotic portal hypertension, is a rare condition that causes high blood pressure in the portal venous system, the network of veins that carry blood from the digestive organs and spleen to the liver.

Portal hypertension most commonly develops because of cirrhosis, a condition in which scarring distorts the liver’s normal structure and makes it harder for blood to flow through it.

In Banti syndrome; however, the liver may look healthy, but the microscopic branches within the liver become narrowed, damaged, or partly blocked. This increases resistance and makes it harder for blood to pass through the liver, increasing pressure in the portal system.

As this pressure builds upstream, blood backs up into the spleen, causing it to become enlarged, called splenomegaly. This can cause some people to experience abdominal fullness or discomfort.

Normally, the spleen filters old or damaged blood cells that circulate through the body. However, because blood is backed up into the spleen, it starts to remove blood cells from circulation more rapidly than usual. This overactivity is called hypersplenism, and it can lead to pancytopenia, meaning low levels of all three major blood-cell types, including red blood cells, white blood cells, and platelets.

This causes a whole list of problems. For example, low red blood cells can cause anemia, leading to fatigue, weakness, or shortness of breath; low white blood cells can make a person more vulnerable to infections; and low platelets can increase their tendency to bruise or bleed.

On top of the problems caused by splenomegaly, the high pressure in the portal system causes blood to flow down alternative routes to return to the systemic circulation, and new connections between the portal and systemic venous systems, called portosystemic collaterals, can develop.