A Rare Case of Preclinical Cushing's Syndrome with "Preclinical" Primary Aldosteronism(Significance of ACTH-loaded adrenal venous sampling in adrenal primary aldosteronism,Proceedings of the 2nd Conference on Adrenal Venous Sampling)

A rare case of preclinical Cushing's syndrome with slight over-production of aldosterone is described. A 54-year-old female patient with a right adrenal mass, 3 cm in diameter on computed tomography, had a history of hypertension for 6 years. The blood pressure was 145/81 mmHg and her plasma potassium level was 3.3 mEq/l. The basal plasma cortisol, ACTH, renin activity and aldosterone levels were within the reference range and the plasma cortisol level was insufficiently suppressed by 8 mg dexamethasone administration. Adrenal venous sampling was performed, which indicated the over-production of both cortisol and aldosterone in the right adrenal tumor. We diagnosed preclinical Cushing's syndrome with slight over-production of aldosterone due to the right adrenal tumor and performed right adrenalectomy. Histopathological examination demonstrated a benign adrenocortical adenoma consisting of clear and compact cells. Post-operatively, her blood pressure and plasma potassium level normalized, and her plasma cortisol was sufficiently suppressed by night-time 1 mg dexamethasone administration. The response to captopril load test normalized. In this case, we assume the possibility that the double production of cortisol and aldosterone may reflect disorganized expression of steroidogenic enzymes usually associated with malignant transformation