Systemic extrapancreatic lesions associated with autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is often associated with systemic extrapancreatic lesions. We studied 31 cases of AIP to clarify the diversity of associated systemic extrapancreatic lesions and the differences between AIP with and without systemic extrapancreatic lesions.

The clinical features and courses were compared by age, sex, and blood chemistry between those with and without systemic extrapancreatic lesions. In addition, we reviewed the available literature on systemic extrapancreatic lesions with AIP.

Seven of the 31 cases of AIP had associated systemic extrapancreatic lesions, which were diagnosed simultaneously with AIP; however, 1 case presenting with various extrapancreatic lesions was diagnosed independently of the AIP lesion. Patients with systemic extrapancreatic lesions needed maintenance steroid therapy for AIP in 4 cases and systemic extrapancreatic lesions in 2 cases; the ratio of cases requiring maintenance steroid therapy was significantly higher among those with systemic extrapancreatic lesions (6/8) than those without (7/23). There were no significant differences between groups with regard to age, sex, extent of narrowing of the main pancreatic duct, and enlargement of the pancreas. gamma-globulin, IgG, and IgG4 levels were significantly higher in patients with AIP with systemic extrapancreatic lesions than those without. The systemic extrapancreatic lesions associated with AIP found in the literature were Sjögren syndrome, ulcerative colitis, retroperitoneal fibrosis, sialadenitis, thyroiditis, and idiopathic thrombocytopenic purpura.

The results of this study suggest that, when encountering a case of AIP with elevated levels of gamma-globulins, IgG, and IgG4, an effort should be made to detect other systemic extrapancreatic abnormalities and initiate steroid administration.