Markedly increased 18F-FDG uptake in a nonfunctioning adrenal adenoma mimicking malignancy.

A 63-year-old woman underwent (18)F-FDG PET/CT searching for the cause of a fever of unknown origin. (18)F-FDG PET/CT incidentally detected a focal area of markedly increased radiopharmaceutical uptake in the right adrenal gland; this finding was suspicious for an adrenal malignancy or a functioning adenoma. Nevertheless, histology and laboratory data demonstrated the presence of a nonfunctioning adenoma. This case highlights that nonfunctioning adrenal adenomas should be considered as possible false-positive (18)F-FDG PET/CT findings for malignancy in the evaluation of adrenal incidentalomas, even when marked (18)F-FDG uptake is revealed.