Adrenal hyperplasia in Cushing's syndrome demonstrated by FDG positron emission tomographic imaging

A 37-year-old woman with severe Cushing's syndrome had no evidence of an adrenal or pituitary source. An ectopic adrenocorticotropic hormone source was considered instead. The results of an indium-111 octreotide scan were interpreted as negative. F-18 fluorodeoxyglucose positron emission tomography (FDG PET) revealed focal uptake in the left mediastinum and symmetric bilateral adrenal uptake. Computed tomography (CT) showed bilateral adrenal hyperplasia corresponding to the adrenal FDG uptake and a mediastinal mass. The mediastinal mass was a paraganglioma on resection. Uptake of FDG in adrenal hyperplasia has not been described before.