IgG4-related cholangitis - distinguishing from other benign biliary strictures: clinical features, imaging, and response to treatment: a retrospective study

Background: IgG4-related cholangitis (IRC) is a rare systemic fibroinflammatory disorder that can affect multiple secretory organs, posing diagnostic challenges. It mimics both benign biliary strictures (BBS) and malignant biliary strictures (MBS). A hallmark feature of IRC is its dramatic response to systemic corticosteroids. Misdiagnosis may lead to incorrect treatment or unwarranted surgical procedures. This study aimed to compare the baseline characteristics, laboratory test results, imaging findings, and treatment responses between IRC and other BBS groups. Methods: We reviewed all patients with a definitive diagnosis of BBS between January 2013 and January 2023. Data on serum bilirubin, serum IgG4 level, stent type, and response to treatment were collected. The baseline characteristics, biliary stricture treatment, and stent indwelling time were compared between the IRC and other BBS groups. Results: A total of 158 patients with BBS were included (IRC, n = 19; other BBS, n = 139). The mean age was 59 years, and 62% were male. No significant difference in comorbidities or initial laboratory results was observed between the two groups. The IRC group had significantly higher rates of jaundice (73.7% vs. 29.7%, p < 0.001) and coexisting autoimmune pancreatitis (52.6% vs. 0%, p < 0.001). Patients with IRC had significantly higher serum IgG4 levels (5.384 g/L vs. 0.838 g/L, p < 0.001) and longer stricture lengths (23 mm vs. 7 mm, p < 0.001). Patients with IRC achieved complete responses to medication without requiring prolonged endoscopic stenting or surgery. Key diagnostic factors for IRC included being male (odds ratio [OR] 3.71, 95% confidence interval [CI] 1.03-13.32, p = 0.045), uniform circumferential bile duct thickening (OR 5.00, 95% CI 1.82-13.69, p = 0.002), long stricture length (> 15 mm) (OR 5.72, 95% CI 2.02-16.19, p = 0.001), The multivariate analysis demonstrated tissue lymphoplasmacytic infiltration (OR 88.38, 95% CI 7.98-978.53, P < 0.001) and Cholangiography type I (OR 22.47, 95% CI 2.63-192.26, p = 0.004). Conclusions: IRC can be distinguished from other BBS through specific clinical and imaging features. Elevated serum IgG4 levels and tissue staining for IgG4-positive cells aid in accurate diagnosis. Recognising IRC, even in low-prevalence areas, guides appropriate treatment and avoids unnecessary surgery.