Is IgG4 immunostaining of duodenal ampullary biopsies alone useful to diagnose autoimmune pancreatitis?

Abstract

The recent article by Moon et al1Moon S.H. Kim M.H. Park D.H. et al.IgG4 immunostaining of duodenal papillary biopsy specimens may be useful for supporting a diagnosis of autoimmune pancreatitis.Gastrointest Endosc. 2010; 71: 940-946Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar was interesting and presented an important examination of IgG4 immunostaining of ampullary biopsy specimens as a potential tool to diagnose autoimmune pancreatitis (AIP). Until recently, only 2 studies had examined the usefulness of this technique, both of which concluded that IgG4 immunostaining of ampullary biopsy specimens is useful to diagnose AIP.2Kamisawa T. Tu Y. Egawa N. et al.A new diagnostic endoscopic tool for autoimmune pancreatitis.Gastrointest Endosc. 2008; 68: 358-361Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar, 3Kubota K. Kato S. Akiyama T. et al.Differentiating sclerosing cholangitis caused by autoimmune pancreatitis and primary sclerosing cholangitis according to endoscopic duodenal papillary features.Gastrointest Endosc. 2008; 68: 1204-1208Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar Moon et al1Moon S.H. Kim M.H. Park D.H. et al.IgG4 immunostaining of duodenal papillary biopsy specimens may be useful for supporting a diagnosis of autoimmune pancreatitis.Gastrointest Endosc. 2010; 71: 940-946Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar also conducted a prospective study. In their study, ampullary biopsy specimens in 53% (10/19) of symptomatic AIP patients were positive with IgG4 immunostaining, whereas biopsy specimens from all the control patients were negative. We agree with these results, but it should be noted that ampullary biopsy specimens show only an increased number of IgG4+ plasma cells. Although there is no doubt that IgG4 immunostaining of ampullary biopsy specimens can provide supportive diagnostic information, it is exceedingly challenging for pathologists to make a histological diagnosis of AIP based only on the number of IgG4+ plasma cells. For this reason, we recently conducted a clinicopathological study based on the hypothesis that bile duct biopsy specimens exhibit histological features that are directly related to the pancreas. Our study4Kawakami H. Zen Y. Kuwatani M. et al.IgG4-related sclerosing cholangitis and autoimmune pancreatitis: histological assessment of biopsies from Vater's ampulla and the bile duct.J Gastroenterol Hepatol. 2010; (In press)Google Scholar revealed that the diagnostic sensitivity of IgG4 immunostaining of both ampullary and bile duct biopsy specimens was 52% (15/29) for symptomatic patients with AIP (n = 26) or IgG4-related sclerosing cholangitis (n = 3). Twenty-one patients (72%) had more than 10 IgG4+ plasma cells in at least either biopsy specimen. Furthermore, the bile duct biopsy specimens not only indicated the number of IgG4+ plasma cells but also showed other characteristic histological features, including striform fibrosis and conspicuous eosinophil infiltration.4Kawakami H. Zen Y. Kuwatani M. et al.IgG4-related sclerosing cholangitis and autoimmune pancreatitis: histological assessment of biopsies from Vater's ampulla and the bile duct.J Gastroenterol Hepatol. 2010; (In press)Google Scholar Taken together, these studies indicate that endoscopists should consider bile duct biopsies and ampullary biopsies at the time of ERCP, especially when AIP is suspected but cannot be definitively diagnosed. IgG4 immunostaining of duodenal papillary biopsy specimens may be useful for supporting a diagnosis of autoimmune pancreatitisGastrointestinal EndoscopyVol. 71Issue 6PreviewAutoimmune pancreatitis (AIP) is now considered to be part of an immunoglobulin G4 (IgG4)-related systemic fibroinflammatory disease. Full-Text PDF ResponseGastrointestinal EndoscopyVol. 72Issue 6PreviewWe would like to thank Dr Kawakami and Dr Zen for their comments. We agree that IgG4 immunostaining of both ampullary and bile duct biopsy specimens increases sensitivity in the diagnosis of autoimmune pancreatitis (AIP), compared with ampullary biopsy alone.1 In cases of suspected AIP with obstructive jaundice, we also perform an endobiliary biopsy routinely at the time of ERCP in order to exclude malignancy.2 IgG4 immunostaining for the bile duct biopsy specimen is also performed to support a diagnosis of AIP. Full-Text PDF