Lobularity in Autoimmune Pancreatitis Was A Steroid-Therapy Responding Endoscopic Ultrasound Finding

Endoscopic ultrasound (EUS) can evaluate morphological changes in various pancreatic diseases. We aimed to identify changes in EUS findings of autoimmune pancreatitis (AIP) in response to steroid therapy.

We enrolled 37 patients with AIP and performed EUS before and 2 weeks after steroid therapy to evaluate EUS findings in response to the therapy. Furthermore, we compared the EUS and histopathological findings on AIP in 2 patients who underwent pancreatectomy.

The EUS findings revealed no significant changes in the prevalence of hyperechoic strands and hypoechoic swelling 2 weeks after steroid therapy. In contrast, the prevalence of lobularity significantly decreased from 48.6% to 21.6% after steroid therapy, with a more pronounced reduction in focal AIP (63.6% to 18.2%). Histopathological analysis revealed that lobularity was corresponded to storiform fibrosis between lobular structures infiltrated with immunoglobulin G4-positive plasma cells.

Lobularity in AIP was the most responsive EUS finding to the steroid therapy. Focal lobularity was corresponded to storiform fibrosis between lobular structures infiltrated by IgG4-positive plasma cells. Thus, our findings might help elucidate the pathogenesis of AIP that is responsive to steroid therapy.