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E2479. Imaging Spectrum of Autoimmune Pancreatitis
Authors
  1. Mohammed Saleh; MD Anderson Cancer Center
  2. Dhakshina Ganeshan; MD Anderson Cancer Center
  3. Priyah Bhosale; MD Anderson Cancer Center
Background
Autoimmune pancreatitis is a rare entity with an estimated prevalence of 10.1 per 100,000 persons (1). Autoimmune pancreatitis refers to heterogeneous autoimmune manifestations that may be IgG4-induced (Type 1) or non-IgG4-induced (Type 2). Type 1 is also termed lymphoplasmacytic sclerosing pancreatitis due to the presence of plasmocytes and lymphocytes in pancreatic tissue upon analysis; Type 1 disease rarely presents as an isolated finding as it is a manifestation of a systemic IgG4 disease. Type 2 is also termed idiopathic duct centric pancreatitis which, unlike type 1 disease, usually presents as an isolated finding (2, 3). Imaging is vital in differentiating autoimmune pancreatitis from other pathologies such as pancreatic adenocarcinomas (4). Unlike other pancreatic pathologies, autoimmune pancreatitis is highly responsive to steroids and accurate diagnosis via imaging is essential to avoid any unnecessary interventions (5). The purpose of this educational exhibit is to describe the imaging spectrum and management of autoimmune pancreatitis.

Educational Goals / Teaching Points
This educational exhibit will describe the incidence and histopathological features of autoimmune pancreatitis, describe the typical and atypical imaging features of both subtypes of autoimmune pancreatitis, describe methods of differentiating these entities from other pancreatic pathologies such as malignancy, and describe the current management of the different subtypes of autoimmune pancreatitis.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
CT and MRI are the most commonly used imaging modalities used to assess pancreatic pathology. We will discuss the imaging protocol for evaluation of autoimmune pancreatitis. Several features have been identified to help identify autoimmune pancreatitis such as the dynamic and delayed enhancement pattern on contrast enhanced MRI and sausage-like pancreatic distension(6, 7). Type 1 autoimmune pancreatitis commonly presents with extra pancreatic manifestations such as renal insufficiency, gastrointestinal symptoms due to inflammatory bowel disease, and pulmonary nodules/adenopathy (8). Correlation with laboratory features such as elevations in the serum IgG4 or gamma globulin level, or the presence of ALA or ANA in the serum can help in the diagnosis (5). Imaging features unique to the subtypes will be discussed in this exhibit.

Conclusion
Imaging plays a very important role in the diagnosis and follow-up of autoimmune pancreatitis. Since these subtypes of pancreatitis are highly responsive to immunotherapy radiologists should be aware of the imaging features that will aid in the early detection and differentiation from other kinds of pancreatitis and malignancy.