What tumor causes Cushing syndrome?

Cushing syndrome is a condition that occurs when your body is exposed to high levels of the hormone cortisol for a long time. It can be caused by taking too much glucocorticoid or steroid hormone medications, but it can also be a result of a tumor that causes the adrenal gland to produce too much cortisol.

Tumors that can cause Cushing syndrome are typically found in two glands – the pituitary gland and the adrenal gland.

Pituitary Adenomas: Most cases of Cushing syndrome are caused by a tumor known as a pituitary adenoma, which is a benign or noncancerous tumor. This type of tumor leads to an overproduction of ACTH (Adrenocorticotropic hormone), a hormone that stimulates the adrenal glands to make cortisol. When a pituitary adenoma is the cause, the condition is known as Cushing disease.

Adrenal Gland Tumors: Sometimes, a tumor can form directly in the adrenal glands located on top of the kidneys. These tumors can be benign or malignant (cancerous), but they can cause the adrenal glands to produce too much cortisol, leading to Cushing syndrome.

Ectopic ACTH Syndrome: In some cases, benign or malignant tumors that develop in other parts of the body can produce ACTH. This condition is known as ectopic ACTH syndrome. Lung tumors are the most common cause of ectopic ACTH syndrome.

It’s important to note that not all tumors, including those in the pituitary and adrenal glands, cause Cushing syndrome. Only tumors that lead to an overproduction of cortisol or ACTH cause this condition. The treatment for Cushing syndrome typically involves addressing the underlying cause, such as surgically removing the tumor.