ACTH-INDEPENDENT MACRONODULAR ADRENOCORTICAL HYPERPLASIA (AIMAH) - REPORT OF 2 CASES AND THE ANALYSIS OF STEROIDOGENIC ACTIVITY IN ADRENAL NODULES

We report clinical findings and steroidogenic activities in adrenal ti ssues in 2 cases of AIMAH. Endocrine studies revealed an undetectable level of plasma ACTH and a diminished circadian rhythm of plasma corti sol. A significant increase in plasma cortisol levels in response to A CTH stimulation was observed in both cases. After the administration o f metyrapone in one case, urinary excretion of 17-hydroxycorticosteroi d (17-OHCS) significantly increased, although the plasma ACTH level di d not respond. Computed tomography showed large masses in both adrenal glands, and bilateral uptake was identified on adrenal scintigraphy. The totals for the bilateral adrenal glands were 98 g and 105 g, respe ctively, and the left adrenal was larger than the right in both cases. Steroid content in the nodules measured by high performance liquid ch romatography (HPLC) showed that the cortisol content was definitely lo wer than that in cortisol-producing adenoma (CPA) and even in normal a drenals. The activities of cytochrome P450c17, P450c21 and P450c11 wer e evaluated in one case, and all of them were reduced in the nodules. Especially that of P450c17 was remarkably reduced. These data suggest that cortisol production in AIMAH is inefficient, and that the cause o f Gushing's syndrome may be related to the marked increase in the numb er of cells or bulk of the tumor.