18F-FDG PET/CT Findings of G-CSF-Producing Gallbladder Cancer.

We report a case of granulocyte colony-stimulating factor (G-CSF)-producing gallbladder cancer in a 64-year-old man. Contrast-enhanced CT showed an exophytic hypoattenuation mass with peripheral enhancement in the gallbladder. 18F-FDG PET/CT showed avid FDG uptake in the gallbladder mass and diffuse FDG uptake in the bone marrow. The patient was diagnosed with G-CSF-producing gallbladder cancer based on an elevated serum level of G-CSF and histological findings. G-CSF-producing tumors are associated with a poor prognosis because of rapid progression. Early and accurate diagnosis of G-CSF-producing tumors based on characteristic PET/CT findings is important to determine treatment strategies and improve prognosis of patients.