Endocrine Abstracts

JOINT1164

Introduction: Ectopic Cushing’s syndrome (ECS) is hypercortisolism caused by an extra-pituitary ACTH-producing tumour, and accounts for 10-20% of all Cushing’s syndrome (CS) cases. The common underline diseases of ECS are small cell lung cancer, bronchial neuroendocrine neoplasia (NENs), pancreatic NENs, thymic NENs, and pheochromocytoma. However, ECS in nasal cancer, especially nasal squamous cell carcinoma is extremely rare.

Case presentation: A 29-year-old pregnant woman presented with reduced olfactory and visual acuity. A contrast-enhanced CT revealed a tumour in the right nasal cavity. Biopsy confirmed poorly differentiated squamous cell carcinoma with neuroendocrine differentiation. She delivered a male infant via cesarean section at 33 weeks and 4 days. Postpartum imaging, including MRI and 18-FDG-PET/CT, revealed the metastases in right pharyngeal lymph nodes and the left femoral neck, derived from inoperable nasal cavity carcinoma. Thus, chemotherapy was initiated, along with proton beam therapy to the primary lesion. Despite first-line (cisplatin and etoposide) and second-line (nivolumab) chemotherapy, the disease progressed with metastases in the liver, pleura, and breasts. Five months after the initial diagnosis, she developed hyperglycemia (plasma glucose 11.4 mmol/l, HbA1c 6.0%) and hypokalemia (K 2.4 mEq/l), prompting referral to our department. A month prior, hypokalemia had not been present. She had typical signs and symptoms of CS as follows; significant elevation of serum morning ACTH (221.0 pg/mL), cortisol (126 µg/dL), and urine free cortisol (3740 µg/day). Lack of cortisol suppression of the high dose dexamethasone test led to the diagnosis of ECS due to nasal cavity carcinoma. She started metyrapone treatment with initial daily dose of 750 mg. Treatment with metyrapone 1000 mg and osilodrostat 2 mg successfully reduced cortisol levels (serum morning cortisol: 13.6 µg/dL, urine free cortisol: 51 µg/day) without serious side effects.

Conclusion: This case highlights the rare occurrence of ECS in nasal squamous cell carcinoma. Although the patient did not initially have the Cushing’s signs, overt symptoms with ECS developed rapidly with disease progression. Further accumulation of cases is needed for better understanding of the characteristics and management of ECS due to nasal squamous cell carcinoma.