We report on a male patient, who presented with a locally advanced cancer of the maxillary sinus. For staging purposes, positron emission tomography (PET)/contrast-enhanced computed tomography (CT) was performed. Incidentally, on the CT portion, bilateral, asymmetric, enlarged adrenal masses were found. Fused PET/CT images demonstrated no significant fluoro-deoxy-glucose (FDG) uptake in those adrenal masses, consisting mainly of cystic, fatty tissue with septae, and low density tissues. Therefore the combined anatomo-metabolic information of the dedicated hybrid PET/CT study reliably unmasked the masses as adrenal myelolipomas, instead of primary malignant adrenocortical or even metastatic disease, with a major impact on further patient management.