Differential Diagnosis of ACTH-Dependent Hypercortisolism: Case Report and Literature Review.

Cushing's disease (CD) is an endocrine condition characterized by an excessive production of adrenocorticotropic hormone (ACTH) by the anterior pituitary, which determines an increase in the production of cortisol in the adrenal glands and secondary clinical manifestations. The differential diagnosis includes a corticotropic pituitary tumor or ACTH-producing ectopic neuroendocrine syndrome (EAS). In addition, non tumoral hypercortisolism (NtH) should be taken into account, which may be clinically indistinguishable from CD. Pituitary magnetic resonance imaging (MRI) with gadolinium is the imaging modality of choice; however, conventional MRI can identify only 50-60% of the cases. This has led to the use of bilateral inferior petrosal sinus sampling and the development of dynamic tests, which may allow etiologic certainty and, thus, avoid unnecessary procedures. This review outlines the evidence underpinning the different diagnostic strategies for this disease.