Purpose of review: Endogenous Cushing's syndrome is adrenocorticotropic hormone (or corticotropin)-independent in 15–20% of cases. Primary Cushing's syndrome is most often secondary to adrenocortical adenomas or carcinomas, and more rarely to bilateral adrenal hyperplasias. Corticotropin-independent cortisol-producing hyperplasia is caused by micronodular diseases, including primary pigmented nodular adrenocortical disease and nonpigmented micronodular hyperplasia and adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. Primary pigmented nodular adrenocortical disease can be found either alone or in the context of Carney complex, a multiple endocrine neoplasia syndrome.
Recent findings: In recent years, the pathophysiology of adrenocortical tumors and hyperplasias became better understood following the identification of genes responsible for syndromes associated with corticotropin-independent Cushing's syndrome and the demonstration of aberrant expression and function of various hormone receptors in adrenocortical adenomas and adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. This article reviews findings on the molecular and genetic aspects of corticotropin-independent Cushing's syndrome including recent gene expression profiling studies of adrenocortical tumors and hyperplasias and animal models that provided clues on the pathogenesis of primary Cushing's syndrome.
Summary: A better understanding of molecular mechanisms involved in adrenocortical tumors and hyperplasias may lead to improved diagnostic and prognostic markers and treatment strategies to assist clinicians in the management of corticotropin-independent Cushing's syndrome.
Division of Endocrinology, Department of Medicine and Research Center, Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, Québec, Canada
Correspondence to Isabelle Bourdeau, MD, Division of Endocrinology, Department of Medicine, Research Center, CHUM-Hôtel-Dieu, 3850 Saint-Urbain Street, Montreal, Quebec, H2W 1T7, Canada Tel: +1 514 890 8000 ext 14833 or 14086; fax: +1 514 412-7204; e-mail: firstname.lastname@example.org