Abstract
Background Autoimmune pancreatitis (AIP) is often
misdiagnosed as pancreatic cancer (PC). Both conditions
accumulate 18F-fluorodeoxyglucose (FDG), so FDG positron
emission tomography (FDG-PET) is not discriminatory.
This study aimed to evaluate the pattern of FDG
accumulation, and the change in FDG uptake after steroid
treatment in AIP and PC.
Methods We compared FDG-PET patterns between 18
patients with AIP and 20 patients with PC, and also evaluated
the short-term changes in FDG uptake after steroid
therapy.
Results FDG uptake was observed in 88.9% in AIP and
90.0% in PC. FDG uptake in extra-abdominal lymph nodes
was seen more frequently in AIP, and uptake in salivary
glands, eyes and biliary ducts was seen only in AIP. Follow-
up PET was performed in 6 AIP patients and in 3 PC
patients. Changes in SUVmax after steroid therapy were
estimated within 1 week in 5 AIP patients and in all 3 PC
patients, retrospectively. In 4 AIP patients, the change in
SUVmax was more than 10%. On the other hand, in PC,
SUVmax increased or remained almost unchanged (within
10%).
Conclusions FDG-PET pattern at baseline, and a
decrease in FDG uptake after a short steroid trial can be