Cushing's syndrome - ectopic

Alternative names

Ectopic Cushing's syndrome

Definition

Ectopic Cushing's syndrome is a condition caused by an adrenocorticotropic hormone (ACTH)-secreting tumor outside the pituitary or adrenal glands.

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 long-term administration of corticosteroid drugs commonly used to treat conditions, such as rheumatoid arthritis and asthma.

Small cell tumors of the lung, tumors of the thymus gland, islet cell tumors of the pancreas, medullary carcinoma of the thyroid, and pheochromocytoma are tumors that can secrete ACTH, although this occurs rarely.

Symptoms

Ectopic Cushing's syndrome tends to present with less dramatic classic Cushing's syndrome features, but more dramatic high blood pressure and low potassium. There may be weight loss due to the underlying cancer.

Classic features of Cushing's syndrome:

• moon face (round, red, and full)
  
• "buffalo hump" - collection of fat between the shoulders
  
• central obesity - protruding abdomen and thin extremities
  
• weakness
  
• headache
  
• acne or superficial skin infections
  
• thirst
  
• increased urination
  
• purple striations on the skin of the abdomen, thighs, and breasts
  
• mental changes
  
• impotence or cessation of menses (loss of menstrual periods)
  

Signs and tests
Tests are done to confirm hypercortisolism, then further tests are done to determine the cause.

Tests that confirm hypercortisolism:

• 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: