Focal intrahepatic strictures: A proposal classification based on diagnosis-treatment experience and systemic review

Table 4 Literature review of nature, causes, etiology, pathology and mechanisms of focal intrahepatic strictures

Nature of FIHS	Causes and factors	Etiology	Pathology and mechanisms	Incidence rate
Benign	Surgery and trauma	Hepatobiliary surgery	Physical injury of bile duct and hepatic artery; Ischemia of bile duct	Unknown
		TACE	Chemical injury;Ischemia of bile duct	0.3%[3]
		RFA	Heat damage; Ischemia of bile duct	17%[4]
	Chronic inflammation	Hepatolithiasis/Bacterial infection	Inflammatory response; Mechanical obstruction	70.6%[5]
		Parasite	Inflammatory response; Mechanical obstruction	Case report[6]
		Mycobacterium tuberculosis	Secondary cholangitis and granuloma	16.7%[7]
		HIV cholangiopathy	Inflammatory and immune response caused by cryptosporidium and cytomegalovirus; Ischemia of bile duct caused by injury of hepatic artery	15%-20%[8]
		SD-PSC	Autoimmune response; Bile duct fibrosis	Case report[9]
		LIH-IgG4-SC	Autoimmune response; Bile duct fibrosis	Case report[10]
		Autoimmune pancreatitis	Autoimmune response; Bile duct fibrosis	24.3%[13]
		Follicular cholangitis	Dense fibrosis of muscularis mucosae with follicular hyperplasia	Case report[14]
	Congenital diseases	Caroli's disease	Hepatic fibrosis; Secondary bile duct sclerosis	13%-80%[15,16]
	Benign tumor	IBPMC	Intraductal growth and mechanical obstruction	Case report[17]
Malignant	Primary malignant tumor	Peritubular infiltrating type of ICC	Periductal infiltration and mechanical obstruction	50%-53%[11,18]
		Intratubular growth type of ICC	Intraductal growth and mechanical obstruction
		HCC	Tumor thrombus	11.8%[11]
		ASC of liver	Chronic cholangitis and mechanical obstruction	Case report[19]
	Metastatic malignancy	Metastatic hepatic carcinoma	Intraductal biliary metastasis and mechanical obstruction	Case report[20]

FIHS: Focal intrahepatic strictures; TACE: Transcatheter arterial chemoembolization; RFA: Radiofrequency ablation; SD-PSC: Small duct primary sclerosing cholangitis; LIH-IgG4-SC: Localized intrahepatic IgG4-related sclerosing cholangitis; IBPMC: Intrahepatic biliary papillary mucinous cystadenoma; ICC: Intrahepatic cholangiocarcinoma; HCC: Hepatocellular carcinoma; ASC: Adenosquamous carcinoma.