SAT-482 - Metastatic Adrenocortical Carcinoma Presenting with Refractory Leg Edema and Severe Hypokalemia

Background
Adrenocortical carcinoma (ACC) is a rare, aggressive endocrine cancer with incidence about 1 to 2 per million yearly. Many tumors are functional, most often causing cortisol and or androgen excess. A mineralocorticoid type presentation is less common and can occur without true aldosterone excess when very high cortisol and steroid precursors activate mineralocorticoid receptors because 11β hydroxysteroid dehydrogenase type 2 (11βHSD2) becomes saturated.
Case Presentation
A 50 year old woman presented with one year of worsening fatigue, progressive bilateral leg edema, palpitations, and episodic perceived tachycardia. Prior outpatient evaluations attributed symptoms to heart disease or menopause. Furosemide started 2 weeks prior did not improve edema. On admission she was afebrile with BMI 29.8, blood pressure 150/90 mmHg, heart rate 90 bpm, and marked bilateral edema. ECG showed normal sinus rhythm and TSH was normal. Basic metabolic panel showed sodium 146 mmol/L, potassium 2.2 mmol/L, chloride 100 mmol/L, bicarbonate 36 mmol/L, consistent with a mineralocorticoid effect. Hormonal testing showed marked cortisol excess with 24 hour urinary free cortisol 1249.1 mcg/24 h and urine cortisol 655.7 mcg/24 h, plus DHEAS 333 mcg/dL. Aldosterone was 255 ng/dL with plasma renin activity 23.58 ng/mL/hr; interpretation was limited by recent loop diuretic exposure and lack of renin suppression, making findings not diagnostic of primary aldosteronism. CT showed a suprarenal mass near the pancreatic tail with multiple liver and lung lesions. Endoscopic ultrasound guided biopsy from the suprarenal region showed malignant adrenocortical cells consistent with ACC; liver biopsy confirmed metastatic ACC. She was started on an 11β hydroxylase inhibitor and mitotane, with oncology follow up near her home.
Conclusion
This case highlights metastatic ACC presenting with refractory edema and a mineralocorticoid type biochemical pattern. Severe cortisol excess can produce hypertension, hypokalemia, and metabolic alkalosis through mineralocorticoid receptor activation when 11βHSD2 is saturated, even without primary aldosterone excess. In patients with persistent edema and this biochemical pattern, particularly when refractory to diuretics, endocrine causes including ACC should be considered.

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