Endoscopic ultrasonographic study of autoimmune pancreatitis and the effect of steroid therapy

Abstract

EUS findings in AIP were similar to those in early-stage CP, and hyperechoic strands and lobularity seem to suggest a condition under which the histology of lobular structures of the pancreatic acini is relatively well-maintained. EUS results had improved within about 2 weeks of steroid therapy.

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

“…The positivity of characteristic ultrasonographic findings of AIP depicted by EUS [15,26] were obviously higher than the current data obtained by abdominal US (Table 1). This difference reflects the ultrasonographic features where the image quality is superior when examined with higher ultrasound frequency, on a nearer target, and without interference.…”

“…To date, several imaging modalities, including CT, MRI (MRCP)13, FDG-PET and EUS [15], have confirmed the steroid response during the initial two weeks. However, repeated use of cross sectional images within such a short interval is a concern in daily clinics for several reasons.…”

“…The steroid response is seen in most cases [9,10], so this response, as depicted in clinical images -coupled with endoscopic ultrasonography guided-fine needle aspiration biopsy (EUS-FNAB) [11] and histological examination for a negative cancer diagnosis -can effectively differentiate AIP from pancreatic cancer [12,13]. Intake of a standard dose of steroid for 1-2 weeks typically results in a response in almost all cases of AIP, as determined by dynamic computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP)/magnetic resonance cholangiopancreatography (MRCP) [13], 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) [14], or EUS [15].…”

Diagnosis Autoimmune Pancreatitis

“…Typically, a linear or band-like structure, depicted as low density by computed tomography (CT) and a hypo-intensity signal by T2-weight magnetic resonance image (MRI), appears at the margin of the enlarged pancreatic parenchyma and is referred to as a "capsule-like rim", reflecting the fibrous tissue [39,42] . Abdominal ultrasonography (US) and EUS show similar findings to those of early chronic pancreatitis, including hyperechoic foci (91%-100%), hyperechoic strands (30%-81%), lobularity (15%-53%), and a hyperechoic wall of the main pancreatic duct (30%) in cases with AIP, and these findings decrease after steroid therapy [33,43] . Ultrasound of typical diffuse-type AIP shows a diffusely enlarged low-echoic pancreas without ductal dilation, or so-called "sausage-like appearance."…”

EUS in the Diagnosis of Autoimmune Pancreatitis

“…Also, EUS features of the pancreatic parenchyma may overlap with some characteristics seen in chronic pancreatitis including the presence of hyperechoic foci, hyperechoic strands, and lobularity ( Figure 6). In a case series with patients given steroid therapy, the parenchymal enlargement, lobularity, and lobular outer margins improved with steroid treatment while the hyperechoic foci and strands remained (43). Finally, EUS may demonstrate a normal appearing pancreas.…”