A case of biliary hamartoma (von Meyenburg complex): CT and MRI findings

Clinical History

The patient was found to have increased gamma-glutamyltransferase and alkaline phosphatase levels on routine laboratory examination.

Imaging Findings

The patient was found to have increased gamma-glutamyltransferase and alkaline phosphatase levels on routine laboratory examination. There was no significant clinical history. On admission, the physical examination revealed only a mild and nontender hepatomegaly. Results of an extensive laboratory examination did not reveal any change in tumoral markers.

The patient subsequently underwent an abdominal US (not shown) which showed many hypo- and hyperechoic lesions (<1.0cm) scattered in both liver lobes. For further evaluation, enhanced abdominal CT confirmed the presence of multiple, non-enhancing, very small, hypodense nodules in both the hepatic lobes. To exclude diffuse liver metastases, MR examination was performed, which confirmed the presence of multiple hepatic nodules, hypointense on T1-weighted images and hyperintense on T2-weighted images. On heavily T2-weighted images the signal intensity of the lesions further increased and was only slightly less than that of cerebrospinal fluid. After gadolinium administration, no enhancement was noted. Intra- and extrahepatic bile ducts were normal on MRCP. No communication between the cystic lesions and the draining biliary duct system was noted. At follow-up examination 6 months later, abdominal CT demonstrated unchanged findings.

Discussion

Biliary microcystic hamartoma or von Meyenburg’s complex is an incompletely developed primitive and aberrant bile ductile that does not connect with normal biliary ducts, resulting in cystic dilatations. They are usually incidentally detected at laparotomy, autopsy of imaging studies. An estimated incidence of 1% to 3% has been reported in autopsy series. Multiple bile duct hamartomas are small (>1cm) benign neoplasm of the liver, pathologically containing cystic dilated bile ducts embedded in a fibrous stroma. Although biliary hamartomas have no clinical manifestations and are generally defined as benign lesions, association with malignancies has been reported. Usually, however, biliary hamartomas are stable and without significant growth over time. The ultrasonographic and CT findings are not specific and are rather confusing, regarding the final diagnosis. At US findings have been described as hypoechoic, hyperechoic, or anechoic small nodules with distal acoustic enhancement. Unenhancd CT usually shows hypodense small hepatic nodules scattered throughout both the liver lobes. Homogeneous enhancement of these lesions after administration of iodinate contrast media has been reported sporadically, whereas, no enhancement is more frequently noted. On MR imaging, biliary hamartoma is generally hypointense compared with liver parenchyma on T1 WI and is strongly hyperintense on T2-WI. On heavily T2 WI, the signal intensity increases further, reaching almost the intensity of the fluid. Biliary hamartomas does not show a characteristic pattern of enhancement after intravenous administration of gadolinium, being reported both homogeneous, thin rim or no enhancement of the lesions, as observed in our case.

Differential Diagnosis List

Final Diagnosis

Biliary hamartoma (von Meyenburg complex)

URL:	https://www.eurorad.org/case/2078
DOI:	10.1594/EURORAD/CASE.2078
ISSN:	1563-4086