Imaging features of autoimmune pancreatitis
Objective: To explore the clinical, pathological, and imaging features of autoimmune pancreatitis (AlP).
Methods: The clinical data of 10 patients (all men; aged 47-80 years, mean 61.3 years) with AlP in our hospital between March 2000 and August 2007 were retrospectively analyzed. gamma-globulin, immunoglobulin C (IgG), rheumatoid factors, and autoantibodies were examined for all cases. The imaging findings were reviewed, which included helical computed tomography (CT), endoscopic ultrasonography (EUS), and B-mode ultrasound in all patients, magnetic resonance cholangiopancreatography (MRCP) in 9 patients, and endoscopic retrograde cholangiopancreatography (ERCP) in 7 patients. Follow-up imaging results were available in 5 patients.
Results: Clinically, the most common early symptoms included obstructive jaundice (9/10) and non-specific abdominal pain (1/10), accompanied by the elevated levels of serum gamma-globulin, IgG or the presence of autoantibodies. Diabetes mellitus was detected at presentation in 2 patients. imaging findings included: CT showed diffuse (n=9) and focal (n=1) enlargement of pancreas. Minimal peripancreatic stranding was found in 7 patients, with no pancreatic pseudocyst and calcification. Six patients had enlarged peripancreatic lymph nodes. After contrast injection for 4 patients, delayed enhancement of the pancreatic parenchyma was observed, along with low-density capsule-like rim surrounding the pancreas. Magnetic resonance imaging showed diffuse enlargement of pancreas in 9 patients. MRCP showed diffuse (n=6) and segmental (n=3) irregular narrowing of the main pancreatic duct. B-mode ultrasound showed diffuse (n=9) and focal (n=1) enlargement of the pancreas. EUS showed diffuse (n=9) and focal (n=1) enlargement with hypoecho. ERCP showed stricture of distal common bile duct and irregular dilation of proximal bile ducts in 7 patients, diffuse stricture in main pancreatic duct in 4 patients, and segmental stricture in 3 patients. During the follow-up, abnormalities of imaging and serum markers were resolved after steroid therapy in 5 patients.
Conclusions: AIP is a distinctive type of chronic pancreatitis that shows specific imaging features.