Peripancreatic vascular involvement in patients with type 1 autoimmune pancreatitis.

Background: Type 1 autoimmune pancreatitis (AIP) is the pancreatic manifestation of IgG4-related disease. However, this benign disease can result in the peripancreatic vascular involvement (PVI) on occasion, which increases the difficulty of diagnosis and treatment of this clinical entity as well as for differentiating it from pancreatic malignancies. Methods: We retrospectively reviewed the information on demographics, clinical presentation, laboratory, imaging and endoscopic findings of 101 hospitalized patients with type 1 AIP treated in our department. All the patients were divided into non-PVI and PVI groups according to the first hospitalized medical data. Univariate and multivariate analyses were performed to analyse the potential predictive parameter(s) of PVI in AIP patients. Results: Among the 101 type 1 AIP patients, 52 (51.5%) exhibited PVI, with a male/female ratio 5.5:1. Their average age was 58.37±8.68 years old. Univariate analysis revealed that the location of pancreatitis lesions, including the pancreatic tail (P=0.010), the presence of splenomegaly (P=0.001) and the white blood cell (WBC) number in peripheral blood (P=0.020), were significantly associated with PVI. The location of pancreatitis lesions, including the pancreatic tail (P=0.023), and the presence of splenomegaly (P=0.010) were found to be independent predictors of the development of PVI by a multivariable regression analysis. A total of 18 out of 25 patients in PVI group who underwent corticosteroid treatment and no less than 6 months radiological follow-up showed improvement in vascular lesions, and no case exhibited exacerbation of PVI lesions during follow-up. Of 36 patients in non-PVI group who were followed up for no less than 6 months, only one case exhibited PVI. Conclusions: This retrospective study demonstrated that type 1 AIP was associated with a high proportion of PVI. Pancreatic tail involvement and splenomegaly may predict the PVI in type 1 AIP. PVI lesions are reversible in a subset of patients.