[Rare causes of Cushing's syndrome]

Endogenous Cushing's syndrome seems to occur more frequently than previously anticipated. Both its initial diagnosis and differential diagnosis of the underlying disorder is undoubtedly challenging but important to identify sufferers among high-risk patients with disorders potentially related to cortisol excess. Apart from pituitary adenoma, adrenal tumor and ectopic ACTH secretion, there are a lot of disorders which rarely result in excessive glucocorticosteroid release and action. Remarkable progress in the area of hormonal assessment, imaging procedures and molecular biology has improved the diagnosis, differentiation and management of various clinical entities associated with development of Cushing's syndrome and let to the identification of some new disorders. Because these disorders may negatively affect survivals and, if not treated, lead to serious complications, it is essential to consider their presence in a differential diagnosis of various symptoms. The aim of this manuscript was to provide an overview of the contemporary etiopathogenesis, diagnosis and treatment of rare forms of Cushing's syndrome.