Case Report: Incidentally Discovered a Rare Cystic Lesion of Liver: Multicystic Biliary Hamartoma.

Multicystic biliary hamartoma (MCBH) is an extremely rare cystic lesion of the liver. A 37-year old male patient was admitted to our hospital for incidentally discovered hepatic cystic lesions on abdominal ultrasonography. Abdominal contrast-enhanced computed tomography (CT) showed a multilocular cystic lesion in the segment VI, with mild enhancement in the septae and peripheral wall within the lesion. Only alanine transaminase (ALT) and carbohydrate antigen 19-9 (CA19-9) increased slightly above normal value. Preoperative tests suggested possibility of a benign mucinous cystic neoplasm (MCN) or intraductal papillary neoplasm of the bile duct (IPNB). Laparoscopic complete resection of the lesion was performed. Histopathological examination showed numerous variably sized ductal structures surrounded by periductal glands and fibrous connective tissues containing small blood vessels and smooth muscle bundles. Immunohistochemical staining (IHC) revealed that dilated ducts were positive for cytokeratin CK19, characteristic for biliary tract. Histopathological findings confirmed diagnosis of multicystic biliary hamartoma (MCBH). No recurrence occurred during 6 months follow-up. In conclusion, MCBH should be differentiating from hepatic cystic lesion and could be resected laparoscopically safely.