Pediatric Longitudinal Cohort Study of Chronic Pancreatitis

Inclusion Criteria: 1\. All patients/parents must sign an informed consent and/or assent indicating that they are aware of the investigational nature of this study. 2 Patients/parents must have signed an authorization for the release of their or their child's protected health information. 3 All children providing samples should fit the ARP or CP inclusion criteria defined below. 4 All children must be under 18 years of age at the time of enrollment. Acute pancreatitis (AP): AP is defined as requiring 2 of the following: 1. Abdominal pain compatible with AP, 2. Serum amylase and/or lipase values ≥3 times upper limits of normal, 3. Imaging findings of AP, such as gland enlargement, acute inflammatory changes, and fluid collections. ARP is defined as: At least 2 episodes of acute pancreatitis with complete resolution of pain and a \>1 month pain-free interval between episodes. Chronic Pancreatitis: Children with at least: 1\. One irreversible structural change\* in the pancreas with or without abdominal pain +/- exocrine pancreatic insufficiency +/- diabetes. \*irreversible structural changes: * Ductal calculi, dilated side branches, parenchymal calcifications found in any imaging (abdominal ultrasound (abd US), magnetic resonance imaging/magnetic resonance cholangiopancreatography (MRI/MRCP), computerized tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP), endoscopic US (EUS). * Ductal obstruction or stricture/dilatation/irregularities that are persistent (for \>2 months) on any imaging. * Parenchymal atrophy, irregular contour, accentuated lobular architecture, cavities alone are not diagnostic findings for CP. * Surgical or pancreatic biopsy specimen demonstrating histopathologic features compatible with CP (acinar atrophy, fibrosis, protein plugs, infiltration with lymphocytes, plasma cells, macrophages). Exclusion Criteria: * Patients must not have any significant medical illnesses that in the investigator's opinion cannot be adequately controlled with appropriate therapy or would compromise the patient's ability to tolerate study interventions.