A Multiloculated Cystic Mass in the Liver

Abstract

Question: A 34-year-old woman was referred to our hospital for a cystic mass in the liver. She visited a local hospital 5 months previously with right upper quadrant pain and had been managed under a suspected diagnosis of liver abscess by aspiration of the lesion and antibiotic medications. The liver lesion did not change remarkably over the 5-month period. Physical examination was unremarkable and she no longer had any symptoms. Laboratory analysis revealed no abnormalities and the results of liver function tests were within reference ranges. Contrast-enhanced computed tomography (CT) showed a 3.5-cm cystic mass in the posterior segment of the liver (Figure A). The mass seemed to be a multilocular mass with tortuous tubular structures crowding together, and the tubular structures were seen more conspicuously on venous phase images. On the CT images taken in the late arterial phase, there was an area of lower attenuation surrounding the cystic mass, which showed similar enhancement as the liver parenchyma on the venous phase images. There was no evidence of mural nodules or enhancing solid portions within the mass. Intrahepatic duct dilation was not present in the surrounding liver. T2-weighted magnetic resonance (MR) images (Figure B) defined the cystic nature of the liver lesion more clearly and gadoxate disodium-enhanced dynamic MR images showed similar features as the CT images. The tortuous, tubular structures were seen with an area of relatively decreased uptake of the contrast media surrounding the lesion on the delayed hepatobiliary phase image (Figure C) obtained 20 minutes after injection of the contrast agent. What is the diagnosis? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. The patient underwent right lobectomy; histopathologic examination revealed localized fibropolycystic liver disease (Figure D). The liver lesion appeared as a mass composed of multiple channels lined by bile duct epithelium with intervening fibrous stroma (Figure E). The gross morphology was similar to microscopic findings of biliary microhamartomas. The difference between the two is that biliary microhamartomas present in smaller sizes (0.5–1.5 cm) and are therefore seen as tiny cysts on CT or MR images, whereas our liver lesion presented in a larger form.1Tohme-Noun C. Cazals D. Noun R. et al.Multiple biliary hamartomas: magnetic resonance features with histopathologic correlation.Eur Radiol. 2008; 18: 493-499Crossref PubMed Scopus (50) Google Scholar The area showing lower attenuation surrounding the cystic mass at the arterial phase was revealed as areas of hemorrhage in the surrounding parenchyma. Intraductal papillary mucinous neoplasm of the bile duct may present with tortuous cystic structures communicating with biliary tree.2Lim J.H. Yoon K.H. Kim S.H. et al.Intraductal papillary mucinous tumor of the bile ducts.Radiographics. 2004; 24: 53-66Crossref PubMed Scopus (110) Google Scholar Absence of biliary communication or intraductal papillary structures can be helpful for accurate diagnosis. The clustered pattern of the channel-like cystic structures help to differentiate between biliary cystadenoma and cystadenocarcinoma because these lesions usually present as a single cyst with unilocular or multilocular appearance.3Anderson S.W. Kruskal J.B. Kane R.A. Benign hepatic tumors and iatrogenic pseudotumors.Radiographics. 2009; 29: 211-229Crossref PubMed Scopus (51) Google Scholar In conclusion, when correlating the microscopic appearance of biliary microhamartoma (a milder form of fibropolycystic diseases) with the gross imaging features of the present case, it may aid in the correct diagnosis of fibropolycystic disease.