[Pre-clinical Cushing's syndrome: report of a case and the review of the literature].

Among 838 consecutive patients who underwent abdominal CT scan, adrenal incidentalloma was detected in 41 cases (4.7%). We performed high (8 mg/day) and low dose (2 mg/day) dexamethasone (DXM) suppression test and diurnal rhythm of plasma cortisol in these patients. Autonomic cortisol production was observed in one hypertensive patient in whom Cushigoid appearance was absent, suggesting pre-clinical Cushing's syndrome. We reviewed the endocrine results of the 65 reported cases of pre-clinical or non-Cushigoid Cushing's syndrome in world and Japanese literature. Urinary cortisol excretion was normal in 77%, plasma cortisol rhythm was absent in 70%, and high dose DXM failed to suppress plasma cortisol in 95% of cases. Plasma ACTH and cortisol showed subnormal to low responses to CRF administration similar to overt Cushing's syndrome. Therefore, CRF-test alone was considered insufficient to differentiate the two disorders. Hypertension and glucose intolerance were present in approximately 50% of cases in otherwise asymptomatic patients. Post-surgical steroid replacement was required in 55% of cases in Japan and in 75% of the cases world-wide. Women were affected more with pre-Cushing's syndrome than men. Peak incidence of the pre-Cushing's syndrome in women was in the forties which was older than that of overt Cushing's syndrome, suggesting that pre-Cushing's syndrome is not the predisposing condition to clinically symptomatic Cushing's syndrome. We consider that endocrine test is necessary in incidentally discovered adrenal tumors to exclude the presence of pre-clinical Cushing's syndrome.