**Abstract**

Autoimmune pancreatitis is a relatively recently identified entity. The dominant type 1 is the pancreatic manifestation of a systemic IgG4-related fibroinflammatory disease. The type 2 has a clearly different histology, its dominant feature is a granulocytic epithelial lesion, and it is independent of IgG4. While type 1 is rather a disease with male dominance in majors than 50-year-old people, no gender difference is observed in type 2, and the disease is more frequently seen in young people. The more frequent initial clinical manifestation is obstructive jaundice in type 1, while abdominal pain and mild acute pancreatitis in type 2. CT and magnetic resonance images are very similar, IgG4 can be normal even in type 1, and the associated involvement of other organs is frequently posterior to the pancreatic manifestation; thus, the distinction of the two types of AIP can be difficult without histology in the everyday clinical practice. Several cases can be undetermined and qualified as Not Otherwise Specified (NOS). However, all types of AIP respond quickly to steroid treatment with a complete recovery. Late prognosis is good, but up to 50% recurrence has been observed in type 1, and several authors have described progression to chronic pancreatitis.

**Keywords:** autoimmune pancreatitis, IgG4-related disease, granulocytic epithelial lesion, histology, steroid treatment, complete recovery
