Biliary Hamartoma of the Liver
Biliary hamartomas (also called von Meyenburg complexes) are small, benign collections of disorganized bile ducts and supporting tissue within the liver. They are congenital, develop during fetal life, and persist into adulthood without causing problems in the vast majority of patients. Biliary hamartomas are commonly identified incidentally on abdominal imaging as small, scattered lesions throughout the liver. They do not affect liver function and almost never require treatment. The main importance is recognizing the finding so it is not mistaken for liver metastases or other concerning lesions.
What is it?
The liver contains an extensive network of bile ducts that collect bile produced by liver cells and channel it toward the main biliary tree, the gallbladder, and the small intestine. During fetal life, the bile ducts develop through a complex remodeling of an early ductal structure called the ductal plate. When small parts of this remodeling do not occur normally, residual clusters of bile ducts can remain embedded within the liver. Biliary hamartomas—also known as von Meyenburg complexes—are these benign clusters of disorganized bile ducts and surrounding fibrous tissue. They are present from birth, persist throughout life, and represent one of the most common benign findings encountered in the liver.
Biliary hamartomas are typically small (most are only a few millimeters in size) and often appear in multiples that are scattered throughout the liver. Individually, they consist of small, dilated, sometimes irregular bile duct–like structures within a background of fibrous tissue, often containing a small amount of bile-like material. The cells lining these structures look normal and benign under the microscope.
Biliary hamartomas are part of the broader spectrum of “ductal plate malformations,” which also includes related but distinct conditions such as polycystic liver disease and Caroli disease. In most patients, biliary hamartomas occur in isolation and have no association with these more clinically significant conditions. In a small minority of patients, however, biliary hamartomas may be seen together with other ductal plate–related findings.
The vast majority of biliary hamartomas cause no symptoms. They do not interfere with bile flow, do not affect liver function, and are almost always identified incidentally on imaging performed for other reasons. Liver function tests are typically normal. The clinical importance of biliary hamartomas lies primarily in correctly identifying them on imaging, since their appearance can sometimes resemble more concerning conditions—particularly multiple small metastases, small cysts, or microabscesses—and avoiding unnecessary additional investigation when characteristic features are present.
Diagnosis is generally made by imaging. On ultrasound, biliary hamartomas may appear as multiple small, well-defined lesions with variable echo patterns, sometimes including small bright spots from microcalcifications or “comet tail” artifacts. On CT with contrast, they typically appear as multiple small, low-attenuation lesions scattered throughout the liver and generally do not show significant contrast enhancement. MRI is often the most useful imaging test for confident diagnosis: biliary hamartomas have a characteristic appearance of multiple small, bright, fluid-like lesions on T2-weighted images, with little or no contrast enhancement on dynamic sequences. MR cholangiopancreatography (MRCP) can show that the small cystic structures generally do not communicate with the larger bile ducts, an important distinguishing feature. When the imaging appearance is typical, biopsy is not needed. In atypical cases—such as larger lesions, unusual appearance, or patients with a known cancer in whom metastatic disease must be excluded—further imaging or, rarely, biopsy may be required.
Important to Know
Biliary hamartomas of the liver almost always require no specific treatment. The lesions are benign, do not affect liver function, and do not change significantly over time. Once the diagnosis is confidently established by imaging, the most important step is reassurance and documentation of the finding in the medical record, so that the same lesions are not misinterpreted as metastases or other concerning findings on future imaging.
Patients with biliary hamartomas can usually maintain normal diet, exercise, and activity levels without restriction. There is no need to avoid alcohol or specific foods solely because of biliary hamartomas, although general healthy habits remain important for overall liver and cardiovascular health.
Follow-up imaging is generally not required for typical biliary hamartomas, particularly when the diagnosis is confidently established on a high-quality study (especially MRI with MRCP). In selected patients—such as those in whom the imaging is atypical, those with a history of cancer, or those undergoing imaging for other reasons—periodic monitoring may be considered. The frequency and type of follow-up are individualized based on the specific findings and overall clinical context.
Although biliary hamartomas are widely considered benign and stable, rare reports have described very occasional development of cholangiocarcinoma in association with extensive biliary hamartoma–like changes. This does not change the routine management of typical biliary hamartomas but is one reason that careful imaging characterization is important, particularly when atypical features are present.
Care is typically coordinated by primary care clinicians and, when relevant, radiologists, hepatologists, and gastroenterologists. Imaging findings are interpreted alongside the patient’s overall clinical context rather than in isolation.
Although biliary hamartoma itself is a benign and asymptomatic finding, any new abdominal symptoms should be evaluated based on their own clinical features rather than automatically attributed to a previously identified hamartoma.
Red flag symptoms include severe upper right abdominal pain, persistent vomiting, jaundice (yellowing of the skin or eyes), dark urine, pale stools, signs of gastrointestinal bleeding, significant abdominal swelling, high fever with chills, or sudden change in known abdominal symptoms. These warrant prompt medical evaluation, as they may indicate liver, biliary, or other abdominal conditions unrelated to the hamartomas.