Case 61 - Mild Cushing Syndrome Associated With Ectopic Corticotropin Secretion

Abstract

Most patients with corticotropin (ACTH)-dependent Cushing syndrome (CS) will have an ACTH-secreting pituitary microadenoma. Approximately 15% of patients with ACTH-dependent CS have an ectopic source of ACTH secretion, with the most common source being a bronchial carcinoid (≈25%). The main clues that a patient may have ectopic ACTH-dependent CS include severe CS as evidenced by spontaneous hypokalemia and 24-hour urinary free cortisol (UFC) >1000 mcg, rapid onset of CS, previous diagnosis of a neuroendocrine tumor, and male sex. Rarely, ectopic ACTH-dependent CS presents with symptoms of mild, long-standing hypercortisolism. Herein we present one such case.