自己免疫性膵炎

Autoimmune pancreatitis

自己免疫性膵炎(AIP)は，亜型(1型，2型)分類なども含めて国際的にも認められつつある新しい疾患である．1型AIPは近年IgG4関連疾患の膵病変としても注目されている．“IgG4関連疾患”からみたAIPである1型AIPの概念，病態，診断，治療について最近の知見を述べた．

Recent studies have suggested the existence of two subtypes of autoimmune pancreatitis (AIP) : type 1 AIP, related to IgG4 (lymphoplasmacytic sclerosing pancreatitis) ; and type 2 AIP, related to a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis).　Compared with type 2 AIP, the clinicopathological features of type 1 AIP, with increased serum IgG4 levels, abundant infiltration of IgG4＋plasmacytes and lymphocytes, autoantibodies, and steroid responsiveness, are more suggestive of abnormal immunity such as autoimmunity.　Moreover, patients with type 1 AIP often have extrapancreatic lesions, such as sclerosing cholangitis, sclerosing sialadenitis, or retroperitoneal fibrosis, showing pathological features similar to those of the pancreatic lesions.　Based on these findings, an international concept of and diagnostic criteria for AIP have been proposed recently.