Table 1. Characteristics of our cases.

Items	Case 1	Case 2	Case 3	Case 4
Gender	Female	Female	Male	Male
Age(y)	21	39	80	61
Clinical Findings	None	Abdominal pain	None	None
Clinical Diagnosis	Biliary cystadenoma	Biliary cystadenoma	Biliary cystadenoma	Mucus-producing cholangio-carcinoma
Operative Procedure	Extended right hepatectomy	Left hepatectomy	Left hepatectomy	Left hepatectomy
OMS	Absence	Presence	Absence	Absence
Luminal communication with bile duct	Presence	Presence	Presence	Presence
Atypicality of intracystic epithelium	Absence	Absence	Presence	Presence
Interstitial infiltration	Absence	Absence	Absence	Presence
Expression of mucin protein	MUC1−/MUC2−	MUC1−/MUC2−	MUC1+/MUC2−	MUC1+/MUC2+
Traditional histopathological diagnosis	Biliary cystadenoma	Biliary cystadenoma	Biliary cystadenoma	Biliary cystadenocarcinoma
New histopathological diagnosis	IPN of the bile duct	MCN and IPN of the bile duct	IPN of the bile duct	IPN of the bile duct

OMS, ovarian mesenchymal stroma; MUC, mucin; IPN, intraductal papillary neoplasm; MCN, mucinous cystic neoplasm.