Incidental Early Pancreatitis Detected on 18 F-FDG and 68 Ga-FAPI-46 PET/CT in a Patient With Metastatic Soft Tissue Sarcoma Undergoing 177 Lu-FAPI-2286 Therapy.

While 18 F-FDG PET remains effective in detecting inflammatory cell infiltration, FAPI (fibroblast-activated protein inhibitor) PET may offer higher sensitivity in fibroblast-mediated inflammatory conditions such as pancreatitis. We present the case of a 73-year-old woman with metastatic solitary fibrous tumor undergoing molecular imaging for theranostic evaluation. Both 18 F-FDG and 68 Ga-FAPI46 PET revealed focal uptake in the pancreatic head with peripancreatic fat stranding on low-dose CT. Notably, FAPI PET/CT also demonstrated diffuse pancreatic uptake suggestive of fibroblast-driven inflammation. Subsequent biochemical and clinical findings confirmed acute pancreatitis. This case highlights the potential of FAPI PET/CT in distinguishing pancreatic inflammation from malignancy.