MON-082 Identification and Management of Ectopic ACTH Syndrome Secondary to Olfactory Neuroblastoma

Abstract Disclosure: B.L. Chang: None. K.G. Romo: None. Y. Chen: None. A. Labadzhyan: None. Background: Ectopic ACTH syndrome is caused by non-pituitary production of ACTH and can manifest as overproduction of cortisol. Olfactory neuroblastoma, or esthesioneuroblastoma, is a malignant tumor of the nasal cavity that comprises about 2% of all sinonasal tract tumors. We present a rare case of ectopic ACTH syndrome due to olfactory neuroblastoma. Clinical Case: A 37-year-old male diagnosed with Kadish stage C olfactory neuroblastoma presented with progressively worsening ataxia and diplopia. Olfactory neuroblastoma was diagnosed in 2018 status post craniofacial resection, chemotherapy with carboplatin and etoposide, and localized radiation. Initial laboratory tests showed severe hypokalemia, and physical exam was significant for resistant hypertension, round/plethoric face, central adiposity, dorsocervical fullness, abdominal striae, lower extremity edema, and irritability. Hormonal evaluation showed markedly elevated ACTH up to 606 pg/mL (7.2-63.3 pg/mL) and AM cortisol up to 105.1 ug/dL (3.7-19.4 ug/dL) on three separate occasions, all of which were not suppressed despite receiving high-dose dexamethasone (4 mg every six hours) for treatment of cerebral edema. 24-hour urine free cortisol was 24,888.3 mcg/24-hr (4.0-50.0 mcg/24-hr). MRI brain revealed extensive intracranial disease recurrence without evidence of a pituitary adenoma, and staging CT scans noted new bilateral diffuse adrenal hyperplasia without nodules. Extensive uptake in the bihemispheric olfactory neuroblastoma recurrence was seen on (68)Ga-DOTATATE PET/CT. New immunohistochemistry was evaluated on the surgical sample from 2018 and stained positive for ACTH, confirming ectopic ACTH production from the olfactory neuroblastoma. Given the extent of tumor burden, surgical resection of recurrent olfactory neuroblastoma was initially not recommended. Metyrapone was used to suppress hypercortisolemia before definitive treatment with bilateral adrenalectomy was performed. Following bilateral adrenalectomy, patient was started on stress-dose glucocorticoids before tapering to standard hydrocortisone replacement. He is scheduled for outpatient evaluation for debulking surgery of the intracranial tumor. Conclusion: Clinicians should consider ectopic production of ACTH from olfactory neuroblastomas in patients who present with cushingoid features. Medical and surgical management for ectopic ACTH-related hypercortisolism can be options for treatment. Medical treatment can be a bridge to definitive surgical management. Presentation: Monday, July 14, 2025