A PROPOSAL FOR DIFFERENTIATION BETWEEN EARLY - AND ADVANCED-STAGE AUTOIMMUNE PANCREATITIS BY ENDOSCOPIC ULTRASONOGRAPHY

Abstract

AIM : We evaluated the characteristic endoscopic ultrasonography (EUS) findings of early autoimmune pancreatitis (AIP).
Methods : Nineteen patients with AIP who underwent EUS and endoscopic retrograde cholangiopancreatography (ERCP) were identified from our database. We reviewed the following features of EUS as being potentially characteristic of early AIP : hyperechoic foci, hyperechoic strands, lobularity, hyperechoic duct margins and reduced echogenicity. According to the Cambridge classification for chronic pancreatitis, we classified AIP into early AIP (Cambridge Grade 0-2) and advanced AIP (Grade 3-5) and examined the histopathological findings in each stage of AIP.
Results : Here were 9 cases of early AIP and 10 cases of advanced AIP. Five of the 9 early cases of AIP showed spontaneous remission without corticosteroid therapy (p<0.05). The EUS findings were as follows (early vs. advanced) ; hyperechoic foci, 100% (9/9) vs. 100% (10/10) ; hyperechoic strands, 66.7% (6/9) vs. 70% (7/10) ; lobularity, 77.8% (7/9) vs. 20% (2/10) ; hyperechoic duct margin, 90% (8/9) vs. 30% (3/10) ; and reduced echogenicity, 88.9% (8/9) vs. 90% (9/10). Lobularity and hyperechoic duct margins were detected at a significantly higher frequency in the early AIP than in advanced AIP patients (p<0.05). In relation to the histopathologic findings, acinar cells were preserved to a better extent in the cases of early AIP, whereas the acinar cells were reduced in number and replaced by massive fibrosis in the patients with advanced AIP.
Conclusions : Lobularity and hyperechoic duct margin are characteristic EUS features of early AIP, which has a more favorable prognosis, showing a higher frequency of spontaneous remission and preservation of acinar cells, than advanced AIP.