18F-FAPI-42 PET/CT Finding in a Patient With Pancreatic Ductal Adenocarcinoma Encapsulated by Immunoglobulin G4-related Autoimmune Pancreatitis Located at the Pancreatic Body

Pancreatic ductal adenocarcinoma (PDAC) encapsulated by IgG4-related autoimmune pancreatitis (AIP) manifests as a rare presentation. A 67-year-old man with IgG4-AIP underwent two 18 F-FAPI-42 PET/CT visualizations. The first PET/CT showed diffuse and intense FAPI uptake in the pancreas. PET/CT follow-up after a period of glucocorticoid treatment suggested focal and intense FAPI uptake along the pancreatic body. The final pathologic diagnosis after surgery was PDAC encapsulated by IgG4-AIP. 18 F-FAPI-42 PET/CT can visualize the progression of diseases and detect patients' treatment responses, which can be used for clinical management of PDAC encapsulated by IgG4-AIP patients.