Abstract: PUB447
Ectopic Cushing Syndrome: A Diagnostic Anomaly of Malignancy
Session Information
Category: Onconephrology
- 1700 Onconephrology
Authors
- Oguntuwase, Elizabeth Feyikemi, Weill Cornell Medicine, New York, New York, United States
- Flombaum, Carlos D., Memorial Sloan Kettering Cancer Center, New York, New York, United States
- Glezerman, Ilya, Memorial Sloan Kettering Cancer Center, New York, New York, United States
- Gutgarts, Victoria, Memorial Sloan Kettering Cancer Center, New York, New York, United States
Introduction
Ectopic Cushing syndrome (ECS) occurs when Adrenocorticotropic hormone (ACTH) is produced outside the pituitary gland. This rare phenomenon increases mortality risk and may be a presenting sign of new or recurrent malignancy. We describe a patient with a history of breast cancer who presents with new metastatic cancer with hypertension, edema, hypokalemia and hypernatremia.
Case Description
58-year-old female with history of breast cancer treated 9 years ago (on tamoxifen), Crohn's disease and nephrolithiasis was referred to the hospital for hypokalemia and concern for cord compression. She had a fall prior to admission with now pathological cervical and T12 fracture managed with dexamethasone and kyphoplasty.
Her blood pressure was 161/87, Pulse 100bpm and oxygen saturation 90% on room air. Physical examination was notable for edema up to the thighs. Laboratory values; included potassium 2.7 (3.3-4.9)mEq/L, sodium 148 (133-143)mEq/L, carbon dioxide 24 (18-29)mEq/L, creatinine 0.7 (0.6-1.1) mg/dL. Fractional Excretion of potassium was 30.8% consistent with renal potassium wasting. PET scan showed metastasis involving the liver, lungs, adrenal, and osseous structures initially concerning for recurrent breast cancer based on prior history. Further work up showed cortisol level of 80.1 (5-25) mcg/dL, 24 hr cortisol 1428 (3.5-45) mcg/24h and ACTH of 610 (7.4-64.3)pg/mL consistent with ECS. Serum aldosterone of <4 (< 21) ng/dl, renin activity of 1.1 (0.6-3.0) ng/ml/hr. She was started on spironolactone 25mg twice daily and metyrapone 250mg every 8 hours. Ketoconazole was avoided due to transaminitis. Her potassium requirements declined, and she was no longer hypertensive. The biopsy from bone lesion was consistent with new small cell lung carcinoma with elevated Chromogranin A levels 2036 (<93) ng/ml.
Discussion
This case highlights the importance of recognizing ECS as a rare paraneoplastic phenomenon. Cortisol and ACTH levels should always be checked in a patient with malignancy, hypertension, and hypokalemia, despite exogenous steroids. Once the diagnosis of ECS is made, treatment is aimed at the cancer as well as steroidogenesis inhibitors (ketoconazole or metyrapone) and mineralocorticoid antagonists (spironolactone). Biopsy in new metastatic disease is key for appropriate diagnosis to avoid anchoring bias and assume that metastases are from prior malignancy.