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

Background: Focal intrahepatic strictures (FIHS) refer to local strictures of the small and medium intrahepatic bile ducts. FIHS are easily misdiagnosed due to their rare incidence, and few studies have focused on the diagnosis and treatment approaches.

Aim: To propose a new classification for FIHS in order to guide its diagnosis and treatment.

Methods: The symptoms, biochemistry results, imaging results, endoscopic examination results and initial and final diagnoses of 6 patients with FIHS admitted between January 2010 and December 2019 were retrospectively analyzed.

Results: The 6 patients were diagnosed with intratubular growth-type intrahepatic cholangiocarcinoma (IG-ICC), recurrent multiple hepatocellular carcinoma (rmHCC) with bile duct tumor thrombus (BDTT), adenosquamous carcinoma (ASC), hepatolithiasis, small duct primary sclerosing cholangitis (SD-PSC) and autoimmune hepatitis (AIH). The initial and final diagnoses were not consistent in 4 patients. Hepatectomy was performed in patients with IG-ICC, ASC and hepatolithiasis according to the locations of their FIHS. Patients with rmHCC with BDTT received lenvatinib/sintilimab, while patients with SD-PSC and AIH received UDCA. We proposed the following classification system for FIHS: type I: FIHS located within one segment of the liver; type II: FIHS located at the confluence of the bile ducts of one segment or two adjacent segments; type III: FIHS connected to the left or right hepatic duct; and type IV: Multiple FIHS located in both lobes of the liver.

Conclusion: Our proposed classification system might help to guide the diagnosis and treatment of FIHS. Hepatectomy should be performed not only for malignant FIHS but also for benign strictures with severe secondary damage that cannot be improved by nonsurgical methods.