August 6, 2009

Autoimmune Pancreatitis

Fig. 1: Axial CT image of a 61-year-old man with abdominal pain shows mild diffuse enlargement of the pancreas, loss of pancreatic lobulation and minimal peripancreatic fat stranding (arrows).

Fig. 2: An ERCP image (injection of pancreatic duct) shows irregular narrowing of the pancreatic duct (arrowheads).

  • Relatively new, rare disease first described in 1995 by Yoshida et al.
  • Chronic pancreatitis characterized by autoimmune inflammatory process (lymphocytic infiltrates) with associated fibrosis of pancreas
  • Associated with immunologic abnormalities: hypergammaglobulinemia, elevated serum IgG4 levels and autoantibodies against carbonic anhydrase and lactoferrin
  • Pathology shows diffusely indurated and firm pancreas, with periductal lymphocytic and plasma cell infiltrates
  • Involvement of the gallbladder, bile ducts, kidney, lung and salivary glands has been described

  • 5-6% of all patients with chronic pancreatitis
  • Men > women, most are > 50 years
  • Mostly associated with other autoimmune disease e.g. rheumatoid arthritis, Sjogren's syndrome, inflammatory bowel disease
  • Responsive to steroid

  • On CT, diffuse pancreatic enlargement, enhanced peripheral rim of hypoattenuation "halo", low attenuation "mass" in pancreatic head, homogeneous attenuation and loss of lobularity
  • Minimal peripancreatic fat stranding
  • Involution of pancreatic tail in long-standing disease
  • On ERCP, focal, diffuse or segmental pancreatic ductal narrowing, disappearance of right-angled branches
Finkelberg DL, Sahani D, Deshpande V, et al. Autoimmune pancreatitis. N Eng J Med 2006;355:2670-2676.

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