Imaging of Focal Autoimmune Pancreatitis and Differentiating It from Pancreatic Cancer
Table 1
Diagnostic criteria for autoimmune pancreatitis proposed by the Korean Society of Gastroenterology.
Criterion I. Imaging (both of the following required)
(1) Imaging (CT or MRI) of pancreatic parenchyma: diffusely/segmentally/focally enlarged gland, occasionally with mass and/or hypoattenuation rim.
(2) Imaging (ERCP or MRCP) of pancreaticobiliary ducts: diffuse/segmental/focal pancreatic ductal narrowing, often with stenosis of bile duct.
Criterion II. Serology (one of the following required)
(1) Elevated levels of serum IgG (>1800 mg/dL) or IgG4 (>135 mg/dL)
(2) Detected autoantibodies.
Criterion III. Histopathology of pancreatic/extrapancreatic lesions (one of the following required)
(1) Lymphoplasmacytic infiltration and fibrosis, often with obliterative phlebitis.
(2) Presence of abundant (>10 cells/high power field) IgG4-positive plasma cells.
Criterion IV. Response to steroids
Resolution/marked improvement of pancreatic/extrapancreatic lesion with steroid therapy.
Probable diagnosis: Criterion V or VI
Criterion V. Unexplained pancreatic disease but only with characteristic pancreatic histology.
Criterion VI. (Both of the following required)
(1) Other organ involvement and/or serologic abnormalities.
(2) Various atypical pancreatic imaging suggesting chronic pancreatitis with negative workup for known etiologies
Adapted from Kim and Lee [6]. CT: computed tomography; ERCP: endoscopic retrograde cholangiopancreatography; IG: immunoglobulin; MRCP: magnetic resonance cholangiopancreatography; MRI: magnetic resonance imaging.
