Steroidogenic Enzyme 17,20-Lyase Activity in Cortisolsecreting and Non-Functioning Adrenocortical Adenomas

The frequency of adrenal incidentalomas has been reported to range between 0.7% and 4% in abdominal computed tomography [1-5], or from 1.4% to 8.7% in autopsy series [6-8]. The widespread application of high resolution imaging techniques, such as computed tomogra‐ phy, magnetic resonance imaging and ultrasonography, has led to an increasing frequency of discovering adrenal incidentalomas. The majority of these lesions are of cortical origin, in‐ clude non-functioning adenomas, adenomas associated with pre-clinical Cushing's syn‐ drome, pheochromocytomas, adrenocortical carcinomas, myelolipomas, ganglioneuromas, metastatic tumors and cysts [9-13]. Adrenal incidentalomas are usually asymptomatic, how‐ ever many of these lesions may secrete weak precursor hormones or active hormones in in‐ sufficient amounts to cause clinically apparent disease. There are reports of several cases of adrenal incidentaloma who had no clinical evidence of Cushing’s syndrome and normal basal steroid hormone secretion, but non-suppressible serum cortisol after dexamethasone administration. These cases were regarded as “pre-clinical Cushing’s syndrome” [14-16] and many of them treated by adrenalectomy, which restored a normal cortisol suppression to dexamethasone.