Autoimmune pancreatitis misdiagnosed as a tumor of the head of the pancreas

Figure 1 A computed tomography scan sagittal slide showing thickening of the pancreatic head with hypo-dense center (arrow) and with no obvious acinari structure.

Figure 2 A coronal reconstruction reinforcing the sagittal finding (arrow).

Figure 3 Chronic inflammation with diffuse fibrosis of the acini (short arrows) and around the small pancreatic ducts (long arrow); HE, × 50.

Figure 4 Numerous plasma cells, positive for IgG4 in inflammatory infiltrate; immunoperoxidase, × 100.

Figure 5 Marked fibrosis and lymphoplasmacytoid infiltration around the middle sized pancreatic ducts showing low grade pancreatic intraepithelial neoplasia (arrows); HE, × 50.