Cushing syndrome refers to all conditions in which the body is exposed to excessive cortisol levels — regardless of the underlying cause.

Possible causes of Cushing syndrome include:

• Exogenous administration of glucocorticoids (the most common cause, e.g., long-term therapy with prednisolone)

• Cushing disease(Specific Cause of Cushing Syndrome)

  Cushing disease is a specific form of Cushing syndrome caused exclusively by an ACTH-producing pituitary adenoma.

  • Cause: Pituitary adenoma → ↑ ACTH → ↑ Cortisol (from the adrenal glands)

  • It is therefore an endogenous, ACTH-dependent form of Cushing syndrome.

• Adrenal tumors (e.g., adenoma, carcinoma)

• Paraneoplastic ACTH production (e.g., small cell lung carcinoma)