Unusual Lesions of the Liver

A 57-year-old man was referred to our hospital because of lesions of the liver discovered as an accidental finding on a magnetic resonance imaging (MRI) of the heart. The MRI was performed because of complaints of dyspnea. His further history revealed autism. At the time of presentation he had no symptoms. Physical examination showed no abnormalities. Routine laboratory results were unremarkable. An MRI of the liver was performed. This showed multiple, cystic lesions scattered diffusely through the liver. These lesions had low signal intensity on T1-weighted images (Figure A), intermediate to high signal intensity on T2-weighted images (Figure B). Some of the lesions showed a variable degree of contrast enhancement after application of gadolinium (arrows). These findings in combination with the clinical background were suggestive of biliary hamartomas. A liver biopsy confirmed the diagnosis (Figure C). Histology analysis revealed slightly dilated structures, lined by cuboidal epithelium embedded in fibrous stroma. The epithelium expressed biliary-type cytokeratin 7.

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Biliary hamartomas, also known as Meyenburg complexes, are rare, benign, congenital biliary tract malformations. They are a part of the spectrum of fibropolycystic diseases of the liver. Biliary hamartomas are mainly incidental findings at laparotomy and autopsy. The clinical presentation is usually asymptomatic. No treatment is required. Biliary hamartomas are typically multiple round or irregular focal lesions of nearly uniform size (up to 15 mm) scattered throughout the liver.1 They can be predominantly solid, both solid and cystic, or predominantly cystic, which explains the imaging features. The differential diagnosis for biliary hamartomas includes metastatic lesions, multiple simple hepatic cysts,2 Caroli's disease, and abscesses. Because of the severe consequences of the differential diagnosis it is important to make the right diagnosis. The definite diagnosis is based on the typical histologic findings, but the imaging features of these lesions interpreted against the clinical background are usually suggestive. Biliary hamartomas are benign, but malignant transformation to cholangiocarcinoma and hepatocellular carcinoma is described in some case reports.3