An unusual case of Cushing's syndrome due to ACTH-independent macronodular adrenal hyperplasia.

: We report a case of Cushing's syndrome due to ACTH-independent macro-nodular adrenal hyperplasia (AIMAH). The patient, a 51-year-old man, had been suffering from poorly controlled arterial hypertension for the previous 6 years and he complained of progressive weight gain, gynecomastia and impotence. Physical examination revealed classic cushingoid features. Endocrine basal assessment showed increased urinary free cortisol (264-600 micrograms/24 hr). Urinary steroid profile showed an increase of total 17-hydroxycorticosteroids (17-OHCS: 23 mg/24 hr), with a threefold increase of tetrahydrocortisol (THF:9.66 mg/24 hr) and of tetrahydrocorticosterone (THB: 1.35 mg/24 hr). Tetrahydrodesossicortisol was only slightly elevated (THS:0.67 mg/24 hr) and tetrahydrodesossicorticosterone was at the inferior limit of the normal range (THDOC: 0.03 mg/24 hr). Total 17-ketosteroids were decreased (17-KS: 3 mg/24 hr). Plasma cortisol level was elevated and without circadian rhythm (26-29 micrograms/dl in the morning, 26-28 micrograms/dl at 24:00 h). DHEAs and free testosterone levels were significantly reduced (106 ng/dl and 3.9 pg/ml respectively). ACTH was undetectable and unresponsive to CRH. Both dexamethasone and octreotide failed to suppress plasma cortisol levels. Abdomen computed tomography scan demonstrated bilaterally enlarged multinodular adrenal glands. Cerebral magnetic resonance revealed no alteration of the pituitary gland. The patient underwent bilateral adrenalectomy. On macroscopic examination, adrenal glands were occupied by multiple yellow nodules and their compressive weight was 190 g, with left adrenal heavier than the right one (120 g and 70 g respectively). Histologically, nodular lesions were predominantly composed of large clear cells, with small foci of "hybrid" cells and adipose tissue metaplasia. Reticularis zone was atrophic. In the immediate post-operatory course pulmonary embolism occurred, despite prophylaxis with low molecular weight heparin. After having recovered from this complication, the patient showed progressive regression of cushingoid status. The findings of increased THF/THS and THB/THDOC ratios were in agreement with a relative hyperfunction of 11-beta-hydroxylase "in vivo", which might have contributed to the hypercortisolism, in addition to the marked increase of secernent adrenal mass.