Ectopic ACTH syndrome

ACTH-secreting non-pituitary tumors (ectopic ACTH syndrome)—15% of cases of endogenous Cushing s syndrome usually from small cell lung carcinoma, bronchial carcinoids, pheochromocytoma, or thymus, pancreatic, ovarian, or thyroid tumor. The tumor is usually disseminated (difficult to localize). 

Ectopic ACTH syndrome refers to excessive ACTH production resulting from an endocrine or nonendocrine tumor, usually of the pancreas, thyroid, or lung (e.g., small-cell lung cancer). 

Ectopic ACTH syndrome Surgery, chemotherapy. Metyrapone (Metopirone) 250-mg capsules 0.5-1 g/day, divided eveiy 4-6 hours 1-2 g/day, divided every 4-6 6 g/day... 

Cushing s disease (caused by a pituitary ACTH-secreting adenoma) or Cushing s syndrome from an adrenal tumour is normally treated by surgical removal of the primary lesion where possible. Cases of ectopic ACTH syndrome associated with carcinoma of the bronchus cannot be treated surgically, and often benefit from medical therapy to control adrenal steroid excess. 

Normal Ciiishing s Syndrome Adrenal Tumor Ectopic ACTH Syndrome... 

Overproduction of cortisol by hyperplastic adrenal cortices can result from oversecretion of ACTH (secondary hypercortisolism) due to a defect at the level of the pituitary or median eminence or to ectopic production of ACTH. The former condition is known as Cushing s disease and the latter as ectopic ACTH syndrome. In both conditions, the adrenal cortex functions normally and secretes cortisol in proportion to the level of ACTH. 

Cushing s disease, which is more prevalent than ectopic ACTH syndrome, can be distinguished from the latter by its glucocorticoid suppressibility. Large doses of dexam-ethasone administered for three consecutive days suppress ACTH secretion. In ectopic ACTH syndrome, malignant transformation in some tissues (notably the lung) induces... 

In the ectopic ACTH syndrome multiple sites of tumors exist, and locating the ectopic site is essential but often difficult. 

Conn RJ, Gorden P. Long-term medical treatment of ectopic ACTH syndrome. South Med J 1998 91 1014-1018. 

Ectopic ACTH syndrome Form of Cushing syndrome in which benign or malignant tumors arise in places other than the pituitary, leading to excessive release of ACTH and subsequently, cortisol into the bloodstream represents approximately 10 to 15 percent of Cushing syndrome cases. 

Other nonpituitary causes of Cushing s syndrome, however, include a primary tumor of the adrenal cortex secreting excessive amounts of cortisol directly into the bloodstream. This disorder also can result from the release of ACTH from secretory nonendocrine nonpituitary neoplasms ( ectopic ACTH syndrome). Cushing s syndrome is often caused by excessive doses of synthetic GCs used to treat a variety of disorders because of their potent anti-inflammatory effects (iatrogenic Cushing s syndrome). 

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