Autoimmune pancreatitis: a guide for the histopathologist.
Autoimmune pancreatitis (AIP) is a distinct form of pancreatitis with a characteristic histological appearance. Clinically and radiologically, many of these patients show enlargement of pancreas and pancreatic duct/bile duct strictures, thus mimicking pancreatic carcinoma. There are 2 forms of the disease: (1) type 1 AIP characterized by storiform type fibrosis, obliterative phlebitis, and elevated numbers of immunoglobulin G4 (IgG4) positive plasma cells, typically >50 per high-power field, and, (2) type 2 AIP characterized by granulocytic epithelial lesions and only occasional IgG4-bearing plasma cells, typically <10 per high-power field. The type 1 variant of AIP is the pancreatic manifestation of IgG4-related disease, thus both pancreatic and extrapancreatic recurrences are common. The type 2 variant is unrelated to IgG4-related disease, and disease recurrence is uncommon. Both forms of the disease show a swift response to immunosuppressive therapy. This review highlights the clinical and pathological differences between the 2 forms of AIP. We also review guidelines that assist in distinguishing AIP from its closest mimic, pancreatic adenocarcinoma.
Department of Pathology, Tufts Medical Center, Boston, Massachusetts, USA.
Shweta
S
Shinagare
Atul B
AB
Shinagare
Vikram
V
Deshpande
D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D005260:Female; D005355:Fibrosis / Q000276:immunology / Q000473:pathology; D006098:Granulocytes / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000000981:diagnostic imaging / Q000473:pathology; D010183:Pancreatic Ducts / Q000000981:diagnostic imaging / Q000473:pathology; D050500:Pancreatitis, Chronic / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D010689:Phlebitis / Q000276:immunology / Q000473:pathology; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology; D011859:Radiography
D015415:Biomarkers; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents