Metachronous Extrapancreatic Lesions in Autoimmune Pancreatitis

Objective Autoimmune pancreatitis (AIP) is frequently associated with various extrapancreatic lesions. The distribution and frequency of extrapancreatic lesions preceding or subsequent to AIP are unknown. The aim of this study was to investigate metachronous extrapancreatic lesions of AIP. Patients and Methods Extrapancreatic lesions were examined clinically, radiologically, and histologically in 56 AIP patients. Results Extrapancreatic lesions were associated in 25 (45%) of 56 AIP patients. Twenty-nine extrapancreatic lesions were detected synchronously with AIP in 18 patients, and 18 lesions were detected metachronously in 11 AIP patients. Fourteen patients had more than 2 extrapancreatic lesions. There was no significant difference in serum IgG4 levels between AIP patients with preceding extrapancreatic lesions and synchronous extrapancreatic lesions. Extrapancreatic lesions preceding AIP were sclerosing sialadenitis (n=8), cervical lymphadenopathy (n=4), swelling of the lacrimal glands (n=2), retroperitoneal fibrosis (n=1), and hilar lymphadenopathy (n=1). Retrospective histopathological examination confirmed that these lesions were compatible with IgG4-related sclerosing disease. Steroid therapy was not given for these initial lesions, and AIP occurred 3 to 48 months after these initial lesions. Swelling of the preceding extrapancreatic lesions persisted when AIP occurred. Extrapancreatic lesions subsequent to AIP were retroperitoneal fibrosis (n=1) and systemic lymphadenopathy (n=1), both of which occurred during follow-up of AIP without steroid therapy. All extrapancreatic lesions improved after steroid therapy. Conclusion Swelling of salivary or lacrimal glands, lymphadenopathy, and retroperitoneal fibrosis can precede AIP. Lymphadenopathy and retroperitoneal fibrosis can occur subsequent to AIP. Recognition of these findings will aid in the correct diagnosis of AIP.