o Autoimmune Pancreatitis
Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis characterized by diffuse enlargement of the pancreas, narrowing of the pancreatic duct, and lymphoplasmacytic infiltration and fibrosis. AIP presents similarly to pancreatic cancer, so definite diagnosis is imperative to avoid unnecessary major surgery.
Type I AIP is the pancreatic manifestation of systemic IgG4-related disease. Histologically, it is a lymphoplasmacytic sclerosing pancreatitis (LPSP). Type 2 AIP, or idiopathic duct-centric pancreatitis, is IgG4 negative and is characterized by granulocytic lesions. Type 2 is more rare and less well understood.
Both types respond to steroid therapy, although type 1 AIP will often (20-60% of the time) relapse (Hart, 2015).
Panel test:
o Immunoglobulin G subclass 4
o Canser antigen –GI (CA-19-9)
o IgG4 (Immunohistochemistry)
References
Guidelines
1. Shimosegawa T, Chari ST, Frulloni L, Kamisawa T, Kawa S, Mino-Kenudson M, Kim MH, Klöppel G, Lerch MM, Löhr M, Notohara K, Okazaki K, Schneider A, Zhang L; International Association of Pancreatology. International consensus diagnostic criteria for autoimmune pancreatitis: guidelines of the International Association of Pancreatology. Pancreas. 2011 Apr;40(3):352-8. PubMed
General References
1. Martins C, Lago P, Sousa P, Araújo T, Davide J, Castro-Poças F, Pedroto I. Type 2 Autoimmune Pancreatitis: A Challenge in the Differential Diagnosis of a Pancreatic Mass. GE Port J Gastroenterol. 2017; 24(6): 296-300. PubMed
2. Stone JH, Brito-Zerón P, Bosch X, Ramos-Casals M. Diagnostic Approach to the Complexity of IgG4-Related Disease. Mayo Clin Proc. 2015; 90(7): 927-39. PubMed
3. Matsubayashi H, Kakushima N, Takizawa K, Tanaka M, Imai K, Hotta K, Ono H. Diagnosis of autoimmune pancreatitis. World J Gastroenterol. 2014; 20(44): 16559-69. PubMed
