Multiple biliary hamartomas

Clinical History

A 48-year-old male with no significant past medical history, presented to the outpatient clinic with severe lower back pain. No history of trauma.
MRI Lumbosacral spine was performed and showed an incidental finding in the liver.
US and MRI liver were performed for further assessment.

Imaging Findings

MRI lumbosacral spine showed partially visualized multiple T2 hyperintense lesions scattered in the entire visible liver. Further evaluation by ultrasound was needed.

Ultrasound showed innumerable small well-defined round hypoechoic lesions throughout the liver, some of them showed comet tail sign.

MRI liver without contrast was performed and showed the liver uniformly studded with innumerable non-communicating cystic lesions, the largest of which was seen measuring around 2 x 2 cm at hepatic segment VII. The cystic lesions revealed low signal intensity in T1WIs & very bright signal intensity in T2WIs. Hepatic parenchyma showed a typical 'starry sky' like appearance.

Discussion

Multiple biliary hamartomas (MBH) or von Meyenburg complexes are rare benign malformations of the intrahepatic bile ducts. They are focal collections of duct-like structures which are lined by biliary epithelium that set in an abundant fibrous stroma and dilated in different degrees [1, 2].

MBH incidence ranging between 0.6% and 2.8%. They are usually asymptomatic and may be diagnosed incidentally at liver biopsy, surgery or at autopsy [3].

MBH is reportedly three times more common in females than males.
The prevalence of MBH on imaging is <1% because most hamartomas measure less than 5 mm and are often not detected, however, the prevalence is ~3% at autopsy [4].

On ultrasound, biliary hamartomas appear as small well-circumscribed lesions scattered throughout the liver, with hyperechoic, hypoechoic, or mixed echogenicity depending on solid, cystic, or mixed components, respectively. The “Comet tail” sign, which is a nonspecific sonographic sign for biliary hamartomas may be seen [5].
On CT, biliary hamartomas appear as hypoattenuating multiple lesions measuing less than 1.5 cm, with more irregular margins than seen in simple hepatic cysts. Compared with simple hepatic cysts, biliary hamartomas are more likely to be uniformly numerous, small in size, typically smaller than the hepatic cysts seen in autosomal-dominant polycystic kidney disease [5].
On MRI, biliary hamartomas are hyperintense on T2-weighted imaging and hypointense on T1-weighted imaging. Predominantly cystic lesions show no enhancement after gadolinium [5].
MRCP shows multiple cystic lesions that do not communicate with the biliary tree [5].
Malignant transformation of biliary hamartoma to cholangiocarcinoma is extremely rare. An isolated finding of biliary hamartomas in a healthy patient requires no further diagnostic workup or treatment [5].

Differential Diagnosis List

Final Diagnosis

Multiple biliary hamartomas.

URL:	https://www.eurorad.org/case/14299
DOI:	10.1594/EURORAD/CASE.14299
ISSN:	1563-4086