Determination of steroid response by abdominal ultrasound in cases with autoimmune pancreatitis

Abstract

Abdominal ultrasound is the most convenient modality for examining the morphology of the pancreas without physical stress. Steroid response is one of the key features of autoimmune pancreatitis; however, visualizing this response has not been evaluated using ultrasonography. Thirty-three consecutive autoimmune pancreatitis cases were retrospectively investigated for pancreatic and extrapancreatic lesions by ultrasonography before steroid therapy (n=33) and at two weeks (n=28) and one month (n=19) after starting oral steroid treatment. Steroid treatment resulted in obvious shrinkage of the pancreatic lesion in 86% of the cases at two weeks and in 97% until one month. The maximum thickness of the pancreatic lesion was reduced from 28 to 22 mm in two weeks (P<0.0001), and pancreatic echographic findings improved in one month. Swelling of the peripancreatic lymph node was recognized in 48% and the aortic wall thickness in 12%, mostly reduced in two weeks (P=0.005). One case of definitive autoimmune pancreatitis revealed a steroid response only by following endoscopic retrograde cholangiopancreatography but not by ultrasonography or computed tomography. Abdominal ultrasound revealed a steroid response in most cases of autoimmune pancreatitis within two weeks. Ultrasonography is suitable for initial confirmation of a steroid response; however, atypical cases showing insufficient response or not fulfilling criteria should undergo further examination.