Ectopic ACTH-dependent Cushing syndrome due to mature ovarian teratoma
Ectopic adrenocorticotropic hormone (ACTH) secretion accounts for 10%–20% of ACTH-dependent Cushing syndrome, with ovarian teratomas being an exceptionally rare source. We present a female in her early 40s with severe Cushing syndrome due to ectopic ACTH secretion from a mature ovarian teratoma. She presented with progressive weight gain, moon facies, dorsocervical fat pad, proximal muscle weakness, hypertension and new-onset diabetes. Biochemical evaluation confirmed ACTH-dependent hypercortisolism with elevated cortisol, plasma ACTH, late-night salivary cortisol, urinary free cortisol and failure of dexamethasone suppression. Bilateral inferior petrosal sinus sampling (IPSS) confirmed an ectopic source. After negative pituitary and thoracoabdominal imaging, pelvic imaging identified a large right ovarian mass. Laparoscopic salpingo-oophorectomy was performed, and histopathology confirmed a mature cystic teratoma with ACTH-positive neuroendocrine cells. Postoperatively, the patient achieved complete clinical and biochemical remission with full hypothalamic-pituitary-adrenal axis recovery at 1 year follow-up. This case underscores the systematic diagnostic approach required for ectopic ACTH syndrome—including biochemical confirmation, IPSS to distinguish pituitary from ectopic sources and comprehensive imaging—as well as the importance of considering uncommon tumour sites, including ovarian teratomas, when standard thoracoabdominal imaging is unrevealing.
