Localized (18)F-fluorodeoxyglucose uptake at the pancreatic head during remission phase of autoimmune pancreatitis: A case report

Autoimmune pancreatitis (AIP) is a unique form of pancreatitis, histopathologically characterized by dense lymphoplasmacytic infiltration and fibrosis of the pancreas with obliterative phlebitis. AIP is associated with a good response to steroid therapy. Differentiation between AIP and pancreatic cancer to determine a preoperative diagnosis is often challenging, despite the use of various diagnostic modalities, including computed tomography (CT), magnetic resonance imaging and endoscopic retrograde cholangiopancreatography. It has been reported that (18)F-fluorodeoxyglucose ((18)F-FDG)-positron emission tomography (PET)/CT may be a useful tool for distinguishing between the two diseases. In the present case report, a 71-year-old male patient presented with a well-circumscribed, solitary, nodular and homogenous (18)F-FDG uptake at the pancreatic head, while receiving maintenance steroid therapy in the remission phase of AIP; preoperatively, the patient had been strongly suspected of having pancreatic cancer. Pathological examination revealed post-treatment relapse of AIP. The present case highlights the diagnostic and management difficulties with AIP in the remission phase. In certain cases, it remains challenging to differentiate the two diseases, even using the latest modalities.