A condition caused by an adrenocorticotropic hormone ( ACTH )-secreting tumor outside the pituitary or adrenal glands .
Alternative Names
Cushing's syndrome - ectopic
Causes, incidence, and risk factors
Cushing's syndrome is due to excess glucocorticoid hormones being secreted over a long period of time. About 15% of cases of Cushing's syndrome are due to ectopic Cushing's syndrome. Ectopic Cushing's syndrome is caused by tumors that secrete adrenocorticotropic hormone ( ACTH ). Other causes of Cushing's syndrome are oversecretion of ACTH by the pituitary gland, a tumor of the adrenal gland, or chronic administration of corticosteroid drugs commonly used to treat conditions, such as rheumatoid arthritis and asthma . Small cell tumors of the lung, thymomas (tumors of the thymus), islet cell tumors of the pancreas, medullary carcinoma of the thyroid , and pheochromocytoma are tumors that can secrete ACTH, although this occurs rarely.
Signs and tests
Tests are done to confirm hypercortisolism , then further tests are done to determine the cause. Tests that confirm:
a 24-hour urine for cortisol and creatinine
a dexamethasone suppression test
serial serum cortisol levels -- do not show diurnal variations Test that determines cause:
serum ACTH , elevated Further signs:
fasting glucose , elevated serum potassium , low
Treatment
The best treatment for Cushing's syndrome that is due to an ectopic ACTH secreting tumor is surgical removal of the tumor. In benign tumors, such as thymomas, or pheochromocytoma s, this is usually possible. However, many tumors are malignant (growing worse and resisting treatment), and have metastasized (spread to other areas) before cortisol excess has been diagnosed, and resection is not possible. Drugs to suppress cortisol secretion may be given in such situations. The drugs include: ketoconazole, aminoglutethimide, or metyrapone.
Expectations (prognosis)
Tumor resection may lead to full recovery, but there is a chance of tumor recurrence. Survival for people with ectopic tumors depends upon the outcome associated with the particular tumor type.
Calling your health care provider
Call your health care provider if symptoms of Cushing's syndrome appear.
Prevention
Prompt treatment of tumors may reduce the risk in some cases. Many cases are not preventable.