Etiopathogeny of Primary Adrenal Hypercortisolism

Primary adrenal hypercortisolism is mainly due to cortisol-producing adrenocortical adenomas, bilateral micronodular or macronodular disease, and adrenal carcinomas. Important advances in the pathophysiology of primary adrenal hypercortisolism have been made in the last few years, partly through the use of new molecular biology tools. Most adrenal abnormalities leading to increased cortisol production involve somatic or germinal mutations of genes encoding elements of the cyclic AMP/protein kinase A signaling pathway, as shown in adrenal adenomas in 2014. One peculiar condition is primary macronodular adrenal hyperplasia (PMAH), which has given rise to new pathophysiological concepts such as regulation of cortisol secretion by illegitimate ligands through aberrant expression of G protein-coupled transmembrane receptors in adrenal nodules and stimulation of cortisol production by local adrenocorticotropic hormone production through autocrine/paracrine mechanisms. These findings provide a basis for the development of targeted therapies as an alternative to surgery. The recent identification of germinal mutations of ARMC5 in PMAH raises the possibility that this is much more frequently an inherited disease than previously suspected. It also offers the possibility of earlier diagnosis of PMAH by genetic screening and, hopefully, of earlier intervention to prevent the onset of hypercortisolism and its complications. The pathophysiology of Cushing's syndrome associated with a subset of adrenal adenomas, including subclinical cortisol-secreting incidentalomas and adrenal carcinomas, remains to be determined.