Definitions & Epidemiology
Type 1 AIP is best defined as the pancreatic manifestation of a systemic fibroinflammatory disorder. In addition to pancreatic involvement, the systemic features of AIP include involvement of the bile duct, kidneys, retroperitoneum, orbits, lymph nodes and salivary glands.[6,22,23,24] Characteristic features of this syndrome include a lymphoplasmacytic infiltrate rich in IgG4-positive cells (≥10 cells per high-power field) in all involved organs, elevation in serum IgG4 levels[5,15,25] and multifocal sclerosis.[6,8,26,27,28] Most of the initial case reports and case series were from Japan but it has been recognized as a rare but distinct entity in the West as well. The true incidence/prevalence of this disease is still unclear owing to lack of prospective natural history studies but estimates from Japan range from 0.82 per 100,000 to 6-8% of pancreatic resections performed for presumed pancreatic cancer.[29,30,31]
Unlike most autoimmune conditions, AIP has a male predominance, with a male:female ratio of 2:1.[29,32,33] The peak age of onset is the sixth and seventh decade.[29,32,33] Early data suggest that Type 2 AIP affects a younger cohort of patients and affect men and women equally.
Expert Rev Gastroenterol Hepatol. 2009;3(2):197-204. © 2009 Expert Reviews, Ltd.
Cite this: Autoimmune Pancreatitis: An Update - Medscape - Apr 01, 2009.