Autoimmune pancreatitis classification, diagnosis, treatment and factors associated with disease reccurence

Austėja Malinauskaitė1, Liucija Mažonaitė2

1Lithuanian University of Health Sciences, Faculty of Medicine, Kaunas, Lithuania

2Lithuanian University of Health Sciences Kaunas Hospital, Departament of Internal medicine, Kaunas, Lithuania


Background. Autoimmune pancreatitis (AIP) is a rare chronic disease characterized by histological features of chronic pancreatic inflammation and clinical features associated with pancreatic pathology. The pathogenesis is related to immunological, genetic and environmental factors.

Aim. To review the classification, diagnosis, and treatment of autoimmune pancreatitis and factors associated with disease relapse.

Methods. The literature used for this review was selected using “Google Scholar”, “Pubmed”, “UpToDate” databases. The search was performed using the following keywords and their combinations: „autoimmune pancreatitis”, “classification”, “extrapancreatic lesions”, “relapse”, “radiological diagnostics”, “immunoglobulin G4” and “pharmacotherapy”.

Results. More often, 80 percent, of AIP cases are diagnosed as type 1 AIP. Upper abdominal ultrasound is the first-choice investigation method for suspecting AIP and evaluating other organ lesions, while endoscopic retrograde cholangiopancreatography (ERCP) is the most sensitive investigation method for differentiating AIP from pancreatic tumors. Histological examination allows to accurately determine the type of AIP. A serum immunoglobulin G4 (IgG4) concentration ≥2 times above the normal range (>280 mg/dl) is a diagnostic criterion for AIP. The most commonly, 88 percent, affected organ is the bile duct. In all cases, the treatment method of first choice is corticosteroid therapy in different regimens. Disease relapse is detected in 60 percent of patients with type 1 and only 5 percent with type 2 AIP and the most common factor is the damage of extrapancreatic organs.

Conclusions. AIP is divided into two types depending on the cells infiltrating the pancreatic tissue and ducts: type 1 AIP, which is classified as an IgG4-related disease, and type 2 AIP. AIP is diagnosed based the results of radiological serological and histological tests, the involvement of other organs and the response to corticosteroid therapy. The first-choice treatment method is corticosteroid therapy. AIP relapses are associated with damage to other organs, at least 2 times higher than the normal limit (>280 mg/dl) IgG4, diffuse enlargement of the pancreas, pancreatic duct stones.

Keywords: autoimmune pancreatitis, classification, extrapancreatic lesions, relapse, radiological diagnostics, immunoglobulin G4, pharmacotherapy.

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