• Notes.
• Osmosis
• Sketchy
• BnB (Adrenal disorders)

• Cushing's syndrome refers to hypercortisolism, regardless of its origin, including chronic glucocorticoid therapy.
• Cushing's disease refers to hypercortisolism caused by an adenoma of the anterior pituitary (microadenoma).

The term Cushing's syndrome is used to describe the signs and symptoms of chronic glucocorticoid excess. Causes of Cushing's syndrome include:

1. Exogenous corticosteroids (iatrogenic Cushing syndrome), which is the most common cause. Excess glucocorticoids suppress the hypothalamic-pituitary-adrenal axis, leading to decreased ACTH and bilateral adrenal atrophy.
2. Endogenous corticosteroids, which could be caused by:
   • Primary hypercortisolism: This includes primary adrenal adenoma, hyperplasia, or carcinoma that increases endogenous corticosteroids, leading to decreased ACTH and atrophy of the uninvolved adrenal gland. This condition is ACTH independent. Most cases are benign adrenocortical adenomas. Adrenal adenoma is usually unilateral and secretes only cortisol. The presence of androgen or mineralocorticoid excess suggests a carcinoma.
   • Secondary hypercortisolism: This is ACTH dependent. Hypersecretion of ACTH results in bilateral hyperplasia of the adrenal zona fasciculata and reticularis. Elevated ACTH, cortisol, adrenal androgen, and deoxycorticosterone are observed.

1- Cushing's disease: This is caused by a pituitary adenoma, usually a microadenoma (less than 1 cm in diameter) and is the most common pathological cause of Cushing's syndrome.

o Increased ACTH not sufficient to cause hyperpigmentation

o Dexamethasone suppressible.

2- Ectopic ACTH Syndrome:

• Most frequently observed in patients with small cell carcinoma of the lung.
• Greater secretion of ACTH compared to Cushing's disease. Hyperpigmentation often present.
• The ectopic site is non-suppressible with dexamethasone.
• Typical features of Cushing's syndrome often absent due to malignancy.