Markedly Increased 18F-FDG Uptake in a Nonfunctioning Adrenal Adenoma Mimicking Malignancy

A 63-year-old woman underwent F-FDG PET/CT searching for the cause of a fever of unknown origin. 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 F-FDG PET/CT findings for malignancy in the evaluation of adrenal incidentalomas, even when marked F-FDG uptake is revealed.