Ectopic Cushing syndrome

Definition

Ectopic Cushing syndrome is a condition in which a tumor outside the pituitary or adrenal glands produces a hormone called adrenocorticotropic hormone (ACTH).

Alternative Names

Cushing syndrome - ectopic

Causes, incidence, and risk factors

Cushing syndrome is the result of too much glucocorticoid hormones being released over a long period of time. About 15% of Cushing syndrome cases are due to ectopic Cushing syndrome.

Ectopic Cushing syndrome is caused by tumors that release adrenocorticotropic hormone (ACTH). Other causes of Cushing syndrome are:

• Excess release of ACTH by the pituitary gland
• Long-term use of corticosteroid drugs (commonly used to treat conditions such as rheumatoid arthritis and asthma)
• Tumor of the adrenal gland

Tumors that can, in rare cases, release ACTH include:

• Islet cell tumors of the pancreas
• Medullary carcinoma of the thyroid
• Small cell tumors of the lung
• Tumors of the thymus gland

Symptoms

Ectopic Cushing syndrome tends to have fewer dramatic symptoms than classic Cushing syndrome, but it can occur with higher blood pressure and a lower potassium level. Weight loss may occur due to cancer.

Symptoms of Cushing syndrome are:

• Abdomen sticks out; arms and legs are thin (central obesity)
• Acne or minor skin infections
• Buffalo hump
• Headache
• Impotence (in men)
• Increased urination
• Menstrual cycle stops (in women)
• Mental changes
• Purple stretch marks on the skin of the abdomen, thighs, and breasts
• Round, red, and full face (moon face)
• Tanning or darkening of the skin
• Thirst
• Weakness

Signs and tests

Tests that may be done include:

• 24-hour urine for cortisol and creatinine
• Blood tests to check ACTH, cortisol, and potassium levels
• Dexamethasone suppression test
• Fasting glucose
• MRI and CT scans to find tumors

Treatment

The best treatment for ectopic Cushing syndrome is surgery to remove the tumor. Surgery is usually possible when the tumor is noncancerous (benign).

In some cases, the tumor is cancerous and spreads to other areas of the body before the health care provider can discover the problem with cortisol production. Surgery may not be possible in these cases, but the doctor may prescribe drugs to block cortisol production.

Expectations (prognosis)

Surgery to remove the tumor may lead to full recovery, but there is a chance that the tumor will come back.

Complications

The tumor may spread or return after surgery. High cortisol levels may continue.

Calling your health care provider

Call your health care provider if you develop symptoms of Cushing syndrome.

Prevention

Prompt treatment of tumors may reduce the risk in some cases. Many cases are not preventable.

References

Arnaldi G, Angeli A, Atkinson AB, et al. Diagnosis and complications of Cushing's syndrome: A consensus statement. J Clin Endocrinol Metab. 2003;88:5595-5602.

Stewart PM. The adrenal cortex. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 14.