Radiological Diagnosis of Autoimmune Pancreatitis (AIP) Type 1: A Case Report

Author(s): Diallo Moustapha, Amar Ndeye Isseu, Ndaw Mame Diarra Bousso, Diack Aminata, Diop Massamba, Diouf Cheikh Tidiane, Fall Amath, Ndiaye Abdou Rahmane, Soko Thierno Omar, Mbengue Ababacar

Introduction: Autoimmune pancreatitis (AIP) is a rare form of chronic inflammatory pancreatitis. It is the pancreatic localization of a systemic autoimmune disease characterized by a fibro-inflammatory lymphoplasmacytic infiltration associated with a serum elevation of IgG4. The imaging plays a key role in diagnosis.

Objective: To display the contribution of imaging in the diagnosis of type 1 PAI

Observation: A 38-year-old man was received for the exploration of cholestatic jaundice that has been evolving for 3 weeks. The CT scan showed diffuse hypertrophy of the pancreas with loss of lobulations and presence of a hypodense peripancreatic halo, without peripancreatic fat infiltration. There was a dilation of the bile ducts upstream of a stenosis with enhancement of the distal bile duct, associated with a focus of hypodensity at the cortical base and not enhanced in the left kidney. The diagnosis of pancreatitis and autoimmune cholangitis was evoked. Magnetic Resonance Imaging (MRI) performed secondarily confirmed pancreatic and biliary involvement with diffuse pancreatic hypertrophy in T1 hyposignal, peripheral halo in T2 and T1 hyposignal and long stenosis without dilatation upstream of the main pancreatic duct. The walls of the bile ducts and of the gallbladder were thickened and moved upward. The dosage of serum IgG4 had shown an elevation that reached up to 10 times normal. Drawing on imaging and serum IgG4 levels, the diagnosis of autoimmune pancreatitis type I, associated with chonlangitis and autoimmune nephritis, was taken as a conclusion. The clinical and biological abnormalities have completely regressed under corticosteroid therapy with a disappearance of the bilio-pancreatic abnormalities on the control imaging.

Conclusion: Type 1 PAI is a rare condition whose diagnosis in practice is based on a range of arguments including typical pancreatic involvement on imaging, elevation of IgG4, histological evidence, and or regression of abnormalities on corticosteroid therapy