EUS features in patients with AIP based on the Rosement classification

Background: Rosemont classification (RC) for chronic pancreatitis (CP) is promising in the diagnosis of autoimmune pancreatitis (AIP), however, endoscopic ultrasound (EUS) features of AIP based on the RC has not been evaluated. Aim: To study the EUS findings based on RC in the diagnosis for AIP. Methods: 38 patients of AIP who underwent EUS were identified from our data base between April 2004 and July 2010. EUS findings taken at the pancreatic body in patient with AIP were studied. We reviewed the following features of EUS according to RC, such as hyperechoic foci with/without shadowing, lobularity with/without honeycombing, cysts, strands, main pancreatic duct (MPD) calculi, irregular main pancreatic duct contour, dilated side branches and hyperechoic MPD margin. We also examined histopathological findings obtained by endoscopic-ultrasound-guided fine needle aspiration biopsy of each stratification of AIP (consistent with CP, suggestive of CP and indeterminate for CP). Finally, we evaluated the rate of spontaneous remission and unfavorable events (relapse) taken the EUS features into consideration. Results: As for the diagnostic stratum based on RC, there were 17 patients with consistent with CP, 13 patients with suggestive of CP and 8 patients with indeterminate for CP. EUS findings; hyperechoic foci with shadowing 57.9% (22/38), lobularity with honeycombing 71.1% (27/38), lobularity without honeycombing 31.6% (12/38), hyperechoic foci without shadowing 44.7% (17/38), cysts 7.9% (3/38), stranding 34.2% (13/38), MPD calculi 0%, irregularity of MPD contour 23.7 (9/38), dilated side branches 44.7% (17/38), MPD dilatation 23.7% (9/38) and hyperechoic duct margin 60.5% (23/38). The most common findings were lobularity with honeycombing as parenchymal feature and hyperechoic duct margin as ductal feature. Regarding the histopathologic findings, acinar cells were preserved in patients with indeterminate for CP or suggestive of CP, besides, the acinar cells disappeared and replaced by massive fibrosis in patients with consistent with CP. Unfavorable event was significantly more recognized in patients with consistent with CP than with suggestive of CP or with indeterminant for CP based on RC (p=0.0258). Conclusions: Our results suggest that RC is potentially useful in the diagnosis and predictable for unfavorable events of AIP.