Autoimmune Pancreatitis, Pancreatic and Extrapancreatic Imaging Findings

Autoimmune Pancreatitis, Pancreatic and Extrapancreatic Imaging Findings Poster No.: R-0074 Congress: RANZCR-AOCR 2012 Type: Educational Exhibit Authors: J. Stegeman, A. Borsaru; Clayton/AU Keywords: Education and training, Education, Ultrasound, MR, CT, Pancreas, Abdomen DOI: 10.1594/ranzcraocr2012/R-0074 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply RANZCR's endorsement, sponsorship or recommendation of the third party, information, product or service. RANZCR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold RANZCR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies,.ppt slideshows,.doc documents and any other multimedia files are not available in the pdf version of presentations. www.ranzcr.edu.au Page 1 of 19

Learning Objectives To review the imaging appearance of IgG4-related sclerosing autoimmune pancreatitis (AIP) and its associated systemic manifestations. Background IgG4-related autoimmune pancreatitis is a form of chronic pancreatitis characterised by florid parenchymal and periductal lymphoplasmacytic infiltrate with fibrosis and obliterative phlebitis. Infiltration of IgG4-positive plasma cells into other body tissues, due to extrapancreatic target antigens, produces the 1 systemic manifestations of the disease. The concept of autoimmune pancreatitis 2 was initially raised by Sarles et al. in 1961. Thought to be responsible for 4-6% of chronic pancreatitis Occurs in adults with a mean age at diagnosis of 55 Male predominance at a ratio of 2:1 Presenting symptoms include painless jaundice, vague abdominal discomfort, weight loss, steathorrea, diabetes Often associated with other autoimmune disorders 3 Imaging Findings OR Procedure Details Pancreas Diffuse (56%) or focal (44%) pancreatic enlargement with effacement of the pancreatic clefts ("sausage-like")(fig. 1 on page 4). Affected areas apear hypoechoic on US (Fig. 2 on page 5), hypo-/ iso-attenuating on CT and hypointense to the hepatic parenchyma on 4 1,4,5 T1WI and iso-/hyper-intense on T2WI on MRI. There is usually decreased contrast enhancement of the affected pancreas in the early phases and moderate delayed contrast enhancement in the late phases on both CT and MRI, a finding likely 4 related to fibrosis. A well-defined pseudocapsule or 'halo', hypodense on CT (Fig. 3 on page 6) and hyperintense on T2WI (seen in 56% of patients)may Page 2 of 19

5 occur. When present, it is thought characteristic for autoimmune pancreatitis. Diffuse or segmental narrowing of the pancreatic duct, as opposed to the dilatation found in pancreatic carcinoma, also occurs. Peripancreatic inflammatory changes, calcification and pseudocysts are uncommon 1,4,5. Biliary tree Most frequently involved extra-pancreatic site of disease (88% of patients). May be an isolated finding. Abnormalities include long segment stenosis, mural thickening and 4 6 7 mural enhancement (Fig. 4 on page 7, Fig. 5 on page 8). May involve any part of biliary tree, including gallbladder (Fig. 6 on page 11), but typically affects extrahepatic portions, often the 8 intrapancreatic common bile duct (Fig. 6 on page 11). Renal disease 4 Occurs in approximately 30% of patients. Renal involvement is typically parenchymal but may also involve the perirenal tissue, the renal sinus or the renal pelvic wall (Fig. 8 on page 14, Fig. 9 on page 13). Lesions demonstrate the same echogenicity, attenuation and enhancement characteristics as affected pancreatic tissue (Fig. 1 on 9 9 page 4). Retroperitoneal fibrosis / sclerosing mesenteritis Retroperitoneal fibrosis occurs in 15% of patients and is indistinguishable from other types of fibrosis - manifesting as an mildly enhancing peri-aortic soft tissue cuff (Fig. 10 on page 10, Fig. 4 11 on page 13). Sclerosing mesenteritis occurs less frequently and demonstrates similar soft tissue encasement around the vessels in the root of the mesentery. Inflammatory bowel disease Is seen in 6-17% of patients with AIP with both Crohn's and ulcerative 1,4 collitis described. Lymphadenopathy - Page 3 of 19

May be peripancreatic or involve more distant groups, including 10 mediastinal and cervical nodes. These may measure up to 20 mm. Salivary, thyroid and lacrimal gland / orbital infiltration The salivary glands may be involved in up to 24% of patients - presenting with symmetric painless adenopathy. AIP is associated with autoimmune thyroiditis and subsequent 4 11 hypothyroidism. Orbital involvement involves the lacrimal glands (Fig. 12 on page 15, Fig. 13 on page 16) but may progress into other orbital structures and be complicated by retinal detachment or optic nerve 12 compression. Pulmonary findings Are protean and include pulmonary nodules or masses, a peribronchovascular pattern (Fig. 14 on page 9), ground glass infiltrate, alveolar interstitial changes with secondary bronchiectasis 13 and honey-combing and frank consolidation. Images for this section: Page 4 of 19

Fig. 1: A diffusely enlarged pancreas demonstrating loss of lobulation and effacement of the pancreatic clefts. Note the absence of surrounding inflammatory changes or peripancreatic fluid. The pancreatic duct is effaced. Page 5 of 19

Fig. 2: An enlarged, well-defined and hypoechoic pancreas. The remainder of the body and tail demonstrated a similar appearance. Page 6 of 19

Fig. 3: A faint hypo-attenuating pseudo-capsule is demonstrated. This would typically appear more conspicuous on a portal venous phase study. Page 7 of 19

Fig. 4: Mural thickening and faint mural enhancement demonstrated in the common bile duct. Note the duct tapering as it courses towards the pancreatic head. Page 8 of 19

Fig. 5: Thickened common hepatic duct. Page 9 of 19

Fig. 14: Mild bronchovascular thickening is demonstrated in the apicoposterior segment of the left upper lobe. Page 10 of 19

Fig. 10: Peri-aortic soft tissue cuff at the level of the inferior mesenteric artery origin. Faint enhancement of the cuff is demonstrated. Page 11 of 19

Fig. 6: Gallbladder mural thickening, note the absence of cholelithiasis. Page 12 of 19

Fig. 7: CT cholangiogram volumetric reconstruction demonstrating stenotic segment at the level of the pancreatic head with proximal biliary dilatation. This is a common pattern seen in AIP and can be confused with pancreatic adenocarcinoma. Fig. 11: The same patient as in figure 10 also demonstrates peri-vascular soft tissue cuffing extending into the common iliac arteries. Page 13 of 19

Fig. 9: Multiple hypo-attenuation cortically-based lesions within both kidneys. A delayed study was not performed in this patient but would typically show late enhancement of the lesions. Note the absence of peri-renal inflammatory change. Page 14 of 19

Fig. 8: Multiple hypoechoic cortically-based lesions in the right kidney. Page 15 of 19

Fig. 12: T1 weighted image demonstrating left lacrimal gland enlargement with signal change extending into the intra-conal space. Page 16 of 19

Fig. 13: T1 weighted contrast enhanced study showing enhancement of the enlarged lacrimal gland and the surrounding soft tissue. Page 17 of 19

Conclusion The radiologist plays a critical role in making the diagnosis of AIP with all three described diagnostic criteria listing radiological findings as essential in making the diagnosis 1,3. It is an important diagnosis to make as treatment with steroids are effective at reversing pancreatic and systemic manifestations of the disease and a missed diagnosis may result in an unecessary pancreatectomy. 3 We would like to thank Mr. Dan Croagh, Consultant Surgeon, for help in obtaining the necessary cases for this review. Personal Information J. Stegeman, Radiology Registrar A. Borsaru, Consultant Radiologist Monash Medical Centre Clayton VICTORIA References 1. Kamisawa T, Okamoto A. IgG4-related sclerosing disease. World J Gastroenterol 2008; 14(25): 3948-3955 2. Sarles H, Sarles JC, Muratore R, Guien C. Chronic inflammatory sclerosis of the pancreas - an autonomous pancreatic disease? Am J Dig Dis 1961; 6: 688-698 3. Zandieh I, Byrne MF. Autoimmune pancreatitis: A review. World J Gastroenterol 2007; 13(47): 6327-6332 4. Vlachou PA, Khalili K, Jang HJ, et al. IgG4-related sclerosing disease: autoimmune pancreatitis and extrapancreaticmanifestations. Radiographics 2011 Sep-Oct; 31(5): 1379-402 5. Sahani D, Kalva S, Farrell J, et al. Autoimmune Pancreatitis: Imaging Features. Radiology 2004 Nov; 233: 345-352. Page 18 of 19

6. Hamano H, Kawa S, Uehara T, et al. Immunoglobulin G4-related lymphoplasmacytic sclerosing cholangitis that mimics infiltrating hilar cholangiocarcinoma: part of a spectrum of autoimmune pancreatitis? Gastrointest Endosc 2005; 62(1): 152-157. 7. Takahashi N, Fletcher JG, Fidler JL, et al. Dual-phase CT of autoimmune pancreatitis: a multireader study. AJR Am J Roentgenol 2008; 190(2): 280-286. 8. Nakazawa T, Ohara H, Sano H, et al. Cholangiography can discriminate sclerosing cholangitis with autoimmune pancreatitis from primary sclerosing cholangitis. Gastrointest Endosc 2004; 60(6): 937-944. 9. Takahashi N, Kawashima A, Fletcher JG, Chari ST. Renal involvement in patients with autoimmune pancreatitis: CT and MR imaging findings. Radiology 2007; 242(3): 791-801. 10. Kamisawa T, Okamoto A. Autoimmune pancreatitis: proposal of IgG4-related sclerosing disease. J Gastroenterol 2006; 41(7): 613-625. 11. Li Y, Nishihara E, Hirokawa M, et al. Distinct clinical, serological, and sonographic characteristics of hashimoto's thyroiditis based with and without IgG4-positive plasma cells. J Clin Endocrinol Metab 2010; 95(3): 1309-1317. 12. Owen K, Lane H, Jones MK. Multifocal fibrosclerosis: a case of thyroiditis and bilateral lacrimal gland involvement. Thyroid 2001; 11(12): 1187-1190. 13. Inoue D, Zen Y, Abo H, et al. Immunoglobulin G4- related lung disease: CT findings with pathologic correlations. Radiology 2009; 251(1): 260-270 Page 19 of 19