Relapse patterns and predictors of IgG4-related diseases involved with autoimmune pancreatitis: A single-center retrospective study of 115 patients.

OBJECTIVE: Autoimmune pancreatitis (AIP) was autoimmune disorder accompanied by clinicopathological manifestation whose concept was established as IgG4-related disease (IgG4-RD). Other IgG4-RDs are often involved with autoimmune pancreatitis, sometimes relapsing despite the favorable response to a steroid therapy. This study aimed to clarify patterns and risk factors for extrapancreatic relapse.

METHODS: We reviewed the data of 115 patients diagnosed with definite AIP type 1, followed up for >1 year. We analyzed two items: the timing and pattern of extrapancreatic relapse, and risk factor for relapse with three common manifestations: IgG4-related sclerosing cholangitis (SC), IgG4-related dacryoadenitis and sialadenitis (DS), and IgG4-related retroperitoneal fibrosis (RF).

RESULTS: Remission was achieved in all patients, except for one patient. The extrapancreatic relapse rates were 11.0%, 19.7%, and 40.5% within 3, 5, and 10 years, respectively. Of 26 patients with extrapancreatic relapse, 9 (34.6%) relapsed with new IgG4-RD. Based on a multivariate analysis, the interval between symptom onset and steroid initiation, and the presence of RF at onset was a significant risk factor for relapse with SC and RF, respectively.

CONCLUSIONS: Our results indicate the possibility of various extrapancreatic relapse patterns especially in AIP with OOI. Patients with delayed initiation of steroid or RF at onset should be carefully followed up as high-risk groups for SC and RF relapse.