Adrenal incidentaloma: an overview of hormonal data from the National Italian Study Group

Abstract

Adrenal masses are more and more frequently detected by adrenal ultrasound, computed tomography or nuclear magnetic resonance carried out for a reason other than the suspicion of adrenal disease (incidentalomas). The findings of an incidentaloma still leaves many diagnostic and therapeutic questions open. We report the results of a multicentric retrospective evaluation of patients with adrenal incidentalomas, performed by a Study Group of the Italian Society of Endocrinology. According to the definition of incidentaloma, exclusion criteria a priori were: severe or paroxysmal hypertension, frank hypokalemia and clinical signs of hypercortisolism or hyperandrogenism. 29 centers participated in the study and the data obtained by questionnaire were collected in 2 centers for final elaboration. Center 1 carried out the epidemiological and clinical evaluation. Basal and dynamic hormonal evaluation of 786 among the 1013 cases recruited were performed in our center (center 2). Functional studies included: diurnal rhythm of cortisol, urinary free cortisol (UFC), ACTH, DHEAS, 17-OH progesterone, testosterone, androstenedione, supine and upright plasma renin activity (PRA) and aldosterone, urinary aldosterone, urinary catecholamines and VMA. The hormonal dynamic evaluation included the overnight dexamethasone suppression test (1 mg), CRH test and ACTH test. In our study, 89% (702 patients) of adrenal incidentalomas were non-hypersecretory masses; 6.2% (49 patients) showed a preclinical Cushing's syndrome (PCS) (at least two altered parameters of pituitary-adrenal axis); 3.4% (27 patients) were pheochromocytomas; 0.89% (7 patients) were aldosteronomas. One tumor was a masculinizing adrenocortical carcinoma. Two hundred sixty patients underwent surgical exploration and the histological diagnosis showed: 138 adenomas (53%), 32 carcinomas (12%), 26 pheochromocytomas (10%). 16 myelolipomas (8%), 13 cystic lesions (5.5%), 7 tumors of neuronal lineage (3%). 12 metastases (4%), 13 others (5%). The 138 patients with adenomas had the following hormonal diagnosis: 103 nonfunctional adenomas (74%), 31 PCS (23%) and 4 cases of hyperaldosteronism (3%). In the patients with PCS an abnormal dexamethasone suppression test was found in 86% of cases (37/41 patients). Values for ACTH were low in 78% (32/41 patients). UFC was elevated in 64% of patients, the diurnal rhythm of cortisol evaluated in 14 patients was absent in 7. Only in 50% of cases DHEAS values (12/24 patients) were decreased, whereas they were normal in the other 50%. Interestingly, 8 patients with normal DHEAS and normal UFC showed nonsuppressible cortisol by dexamethasone test (1 mg). Blunted ACTH response to CRH was detected in 9 of 14 patients (64%). Thus our data suggest that the best parameter for evaluating subclinical hypercortisolism seems to be the overnight dexamethasone suppression test. In 27 patients with pheochromocytoma 24-hour urinary catecholamine and VMA levels were elevated in 86 and 46% of cases respectively. In 7 patients with hyperaldosteronism upright PRA was suppressed in 100% of cases and aldosterone plasma levels were elevated in 6 patients (86%); serum potassium level was slightly decreased in 60% of cases. In 86 of 138 histologically proven adenomas, DHEAS levels were: normal in 59% of patients, decreased in 36% and elevated in 4.6%, whereas in 22 of 32 cortical carcinomas evaluated. DHEAS levels were normal in 63% of cases, decreased in 18% and elevated 18%. Post-ACTH 17-OH progesterone levels were elevated in 52% (62/118 patients) of non-functioning adenomas and in 2 of 4 carcinomas. Not enough data are yet available postoperatively. In summary, endocrine evaluation can lead to the identification of a nonnegligible number of cases of clinically unsuspected pheochromocytomas and subtle hypercortisolism (about 3.4 and 6.2%, respectively of all adrenal incidentalomas), while cases of primary subclinical aldosteronism are rarely found. (ABSTRACT TRUNCATED)