Bile duct hamartoma - Liver -

This article will help you read and understand your pathology report for bile duct hamartoma of the liver.

by Alexandra States, MD and Stephanie Reid, MD FRCPC, reviewed on May 18, 2020

Quick Facts

  • A bile duct hamartoma is a non-cancerous liver tumour made up of abnormal bile ducts.
  • Most have no known cause and are found incidentally.
  • Also called a von Meyenburg Complex, named after the Swiss pathologist who first described them.

The liver and bile ducts

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 like 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 which 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. 

What is a hamartoma?

A hamartoma is a non-cancerous type of tumour. The cells in a hamartoma are disorganized and have no function. A hamartoma can be made of one type of cells or several different types of cells. The types of cells found in a hamartoma are usually similar to those found in the location of the body where the hamartoma developed.

What is a bile duct hamartoma?

A bile duct hamartoma is a non-cancerous liver tumour made up of disorganized bile ducts. Pathologists often describe a bile duct hamartoma as a malformation to differentiate it from other kinds of tumours. Another name for this tumour is von Meyenburg complex.

Bile duct hamartoma 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.

Bile duct hamartomas 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 hamartoma 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 bile duct hamartoma and a cancer without a microscope.

How do pathologists make this diagnosis?

Pathologists make this diagnosis by looking at a tissue sample from the liver under the microscope. The tissue sample is usually removed in a procedure called a biopsy or a resection.

When viewed under the microscope, a bile duct hamartoma looks like an abnormal collection of ducts surrounded by normal liver.  The ducts in a hamartoma 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 a hamartoma are not connected to the biliary tree so bile cannot flow from these ducts out of the liver.

No atypia or atypical cells means that the cells inside the ducts did not look abnormal. No mitoses or mitotic figures means that the cells inside the ducts were not dividing to create new tumour cells. No atypia and no mitoses are typical features of a non-cancerous tumour.

Conditions associated with multiple bile duct hamartomas

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 multiple bile duct hamartomas. Other conditions associated with multiple bile duct hamartomas include congenital hepatic fibrosis and Caroli disease.

Treatment

No treatment is necessary for most bile duct hamartomas. However, if your doctor believes you may have a condition, such as fibrocystic liver disease, he or she may offer you treatment.

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