A von Meyenburg complex is a type of non-cancerous liver tumour called a hamartoma. For this reason, another name for a von Meyenburg complex is a bile duct hamartoma. Pathologists often describe a von Meyenburg complex as a malformation to differentiate it from other kinds of tumours.
von Meyenburg complex is a common type of liver tumour seen in approximately 3-6% of the population. Some may appear before birth during the time in fetal development when the liver and bile ducts are first forming. Most bile duct hamartomas are called sporadic because they have no known cause.
The liver is a large organ found in the right upper part of the abdomen, just below the ribs. Most of the liver is made up of special cells called hepatocytes. The liver acts as a factory, producing chemical products such as proteins that our body uses every day. One of the most important products made by the liver is bile. Bile is a liquid that the body uses to digest food. The liver also acts like a recycling plant removing waste and toxins from the body.
The bile duct system, often called the biliary tree, is a group of tubes that connect the liver, and gallbladder to the intestine. They allow bile and other materials produced by the liver to travel into the intestine, where they help with digestion or are removed from the body as stool.
Typically, von Meyenburg complexes do not cause any symptoms and are usually found during an operation for an unrelated issue or at autopsy. Most are small (less than 0.5 cm) and are located just below the covering of the liver (liver capsule). When examined without a microscope most look like a grey, white, or green spot on the surface of the liver.
If discovered during an operation, the surgeon may ask a pathologist to look at a tissue sample from the tumour under the microscope. This is called a frozen section or intraoperative consultation. This procedure is performed because it can be difficult to tell the difference between a von Meyenburg complex and cancer without a microscope.
When viewed under the microscope, a von Meyenburg complex looks like an abnormal collection of bile ducts surrounded by the normal liver. The bile ducts in the tumour are often larger and less round than normal bile ducts. Some of the abnormal ducts may be filled with bile. However, unlike normal bile ducts, the ducts in this tumour are not connected to the biliary tree so bile cannot flow from these ducts out of the liver.
Fibrocystic liver disease is a condition where a person develops abnormal spaces in the liver called cysts. People with fibrocystic liver disease may also develop more than one of these tumours. Other conditions associated with more than one von Meyenburg complex includes congenital hepatic fibrosis and Caroli disease.
No treatment is necessary for most of these tumours. However, if your doctor believes you may have a condition, such as fibrocystic liver disease, he or she may offer you treatment.