Abstract
BACKGROUND: Multicystic biliary hamartoma (MCBH) is an extremely rare benign liver lesion characterized by a gross well-circumscribed multicystic honeycomb appearance. This report presents a MCBH case with a marked peribiliary gland component which showed unusual histology. CASE PRESENTATION: A 63-year-old Japanese male was admitted to our hospital for a detailed examination of a hepatic cystic lesion, which was originally detected 14 years ago and had slowly enlarged. A preoperative imaging study revealed a well-demarcated multicystic lesion without communication to the biliary tracts. The possible clinical diagnoses were mucinous cystic neoplasm (MCN) or MCBH. The lesion was successfully resected by purely laparoscopic right anterior sectionectomy. The cut surfaces of resected specimens grossly exhibited a well-circumscribed multicystic lesion with a thick septum. Histologically, the cyst wall was covered by cuboidal epithelial cells resembling epithelium of the bile duct while abundant small ducts, which morphologically resembled peribiliary glands, were observed among the fibrous stroma of the thick septum. Although possible pathological diagnosis varied, including intrahepatic cholangiocarcinoma, intraductal papillary neoplasm of the bile duct, biliary adenofibroma, MCN and MCBH, the lesion was finally diagnosed as MCBH with a marked peribiliary gland component. CONCLUSIONS: MCBH can contain abundant peribiliary glands in the fibrous stroma. A pathologist should be careful not to diagnose such peribiliary glands in MCBH as neoplastic glands.