Autoimmune pancreatitis as a risk factor of pancreatic cancer.

Abstract

Background: Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that presents clinically with obstructive icterus, histologically with infiltration of pancreatic parenchyma by inflammatory cells leading to chronic inflammation with fibrosis, and therapeutically with good response to corticosteroid therapy. Clinically, it may resemble malignant disease, making diagnosis difficult and requiring a multidisciplinary team (gastroenterologist, endoscopist, radiologist, surgeon, pathologist). Two types of AIP are distinguished. Type 1 is associated with elevated serum immunoglobulin IgG4 and systemic manifestations (IgG4 related diseases). Type 2, without IgG4 elevation, is typically associated with the occurrence of idiopathic inflammatory bowel disease, especially ulcerative colitis. The first line treatment of symptomatic AIP is corticotherapy with an initial dose of 0.6-1 mg/kg/day for the first 2-4 weeks, followed by a gradual de-escalation to prevent frequent relapses. Chronic inflammation, or chronic pancreatitis, is a well-known risk factor for the development of malignancy. The association between carcinogenesis and AIP is widely discussed, but due to the rarity of the disease and a small number of studies, risk estimates vary. Pancreatic carcinoma development is most common in patients with type 1 autoimmune pancreatitis. However, it has been observed that the incidence of extra-pancreatic cancer (stomach, lung, and prostate cancer) is often equal or even higher. It is also considered that AIP may develop from coexisting malignancies as a paraneoplastic syndrome. Screening of patients with AIP for potential carcinogenesis should not be overlooked.

Purpose: The aim of this review article is to point out a rare (autoimmune) form of chronic pancreatitis with the necessity of follow up with regard to the potential risk of malignancy.