The role of endoscopic ultrasonography in diagnosis and treatment of autoimmune pancreatitis

Background: Although endoscopic ultrasonography (EUS) is useful for diagnosis of pancreatic diseases, EUS findings are not employed in the clinical diagnostic criteria for autoimmune pancreatitis (AIP). Objectives: We assessed EUS findings in AIP and retrospectively analyzed them before and after steroid therapy. Methods: Twenty-one patients with AIP who received steroid therapy underwent EUS. Following seven EUS findings for AIP (a) hyperechoic foci, (b) strands, (c) lobularity, (d) reduced echogenicity, (e) capsule-like rim, (f) focal mass forming, and (g) contrast imaging pattern (poor vascular pattern) by contrast agent were assessed before and after steroid therapy. The total numbers of positive EUS findings before and after the steroid therapy were compared. Results: EUS findings before steroid therapy a, b, c, d, e, f, and g were observed in 100%, 91%, 86%, 91%, 86%, 52%, and 48%, respectively. EUS findings after steroid therapy a, b, c, d, e, f, and g were observed in 91%, 57%, 24%, 67%, 29%, 14%, and 10%, respectively. Strands, lobularity, capsule-like rim, focal mass forming, and contrast imaging pattern decreased significantly after steroid therapy (P < 0.05). The total number of positive EUS findings after the steroid therapy (5.1 ± 0.29) was significantly lower than their numbers before treatment (2.81 ± 0.13) (P < 0.001). Conclusion: Strands, lobularity, capsule-like rim, focal mass forming, and poor vascular pattern may reflect the disease activity of AIP. EUS is useful for the evaluation of response to steroid therapy.