Imaging studies in Cushing’s syndrome

Cushing’s syndrome (CS) is a rare (0.2%) cause of arterial hypertension, with an estimated annual incidence of less than 1 per 100,000. Primary hypercortisolism may be of pituitary or ectopic origin, or adreno-corticotropic hormone (ACTH)-independent. When iatrogenic causes of hypercortisolism (secondary) have been excluded, spontaneous CS should be considered, and several endocrinological tests should be performed, with the aim of distinguish between ACTH-dependent and independent CS. In this setting, preoperative imaging procedures are also required. The most frequent CS is pituitary disfunction, which is due to an excess of ACTH and subsequent hyperstimulation of the adrenal cortex, while cortisol-secreting adrenocortical tumors, and the rare primary nodular hyperplasia account for about 15-20% of cases. Both pituitary and adrenal imaging techniques, such as magnetic resonance imaging (MR) and multidetector computed tomography (CT) scan are usually performed. Invasive localizing procedures (selective inferior petrosal sinus sampling), nuclear medicine studies of the adrenal glands (131I-norcholesterol scintigraphy), positron emission tomography (PET), as well as 18F-fluoro-2-deoxyglucose (FDG)-PET/CT, are required only in selected cases.