ectopic ACTH syndrome
Cushing syndrome caused by excessive ACTH secretion from non-pituitary neuroendocrine tumors.
Full Definition
Ectopic ACTH syndrome is a form of Cushing syndrome caused by inappropriate secretion of adrenocorticotropic hormone (ACTH) from non-pituitary sources, typically neuroendocrine tumors. Common sources include lung tumors (particularly small cell lung cancer), pancreatic islet cell tumors, and carcinoid tumors. Unlike pituitary-dependent Cushing disease, ectopic ACTH syndrome often presents with rapid onset of severe symptoms and may be associated with hypokalemia and metabolic alkalosis. Diagnosis requires demonstration of elevated ACTH levels with failure to suppress cortisol production during high-dose dexamethasone suppression testing. Treatment focuses on managing the underlying tumor and controlling hypercortisolism.
Usage
Usage note: Always capitalize ACTH; use 'ectopic ACTH syndrome' rather than 'ectopic Cushing syndrome' for precision.
In Context
- "The patient's rapid-onset Cushing syndrome with markedly elevated ACTH suggested ectopic ACTH syndrome." — Endocrinology consultation
- "Octreotide scintigraphy was performed to localize the source of ectopic ACTH syndrome." — Nuclear medicine report