Autoimmune pancreatitis with atypical imaging findings that mimicked an endocrine tumor

Figure 3 Histological examination of periampular biopsies (notice that both duodenal mucosa and pancreatic parenchyma are visible). A, B: Hematoxylin-eosin staining (A: × 125, B: × 500): atrophic acini surrounded by a fibrous stroma, associated with periductal lymphoplasmocytic infiltration; C, D: Anti-IgG4 immunostaining (C: × 125, D: × 500): the plasma cell infiltration expresses IgG4.