Autoimmune Pancreatitis and Diagnostic Criteria

Autoimmune pancreatitis is a unique form of chronic pancreatitis with autoimmune phenomena, including hypergammaglobulinemia, lymphoplasmacytic infiltration, and responsiveness to corticosteroid therapy. Autoimmune pancreatitis tends to affect elderly males and it presents with pancreatic swelling and irregular narrowing of the pancreatic duct. The symptoms of autoimmune pancreatitis mimic the clinical features of pancreatic cancer; thus, it is important to differentiate between the two conditions. Autoimmune pancreatitis is also characterized by high serum IgG4 concentrations and infiltration of IgG4-bearing plasma cells into the pancreatic tissue. Although these are considered serological and histological hallmarks of autoimmune pancreatitis, the role of IgG4 in the pathogenesis of the disease remains unclear. Furthermore, many cases are complicated by extra-pancreatic manifestations with pathological findings similar to those observed in the pancreatic lesions; these extra-pancreatic manifestations tend to respond favorably to corticosteroid therapy. Autoimmune pancreatitis is now regarded as a member of a new class of IgG4-related disease. Due to inconsistencies in the diagnostic criteria for autoimmune pancreatitis, there is a need for an international consensus on this disease.