Currently, adrenal masses are discovered incidentally in 0.35–5% of patients imaged with computed tomography (CT) and are referred to as adrenal incidentalomas [1,2]. As a result, the diagnostic dilemma of separating the small fraction of hypersecretory and/or malignant masses from the majority that are nonhypersecretory adrenal adenomas has become common. Given the fourfold greater autopsy incidence of adrenal adenomas compared with the radiographic incidence, and the oncology data that only 20–41% of adrenal metastases are detected by CT [1,3], it is likely that an increase in prevalence will occur if the spatial resolving capacity of abdominal imaging improves, if abdominal imaging occurs more frequently, and if routine abdominal imaging slice thickness is decreased.

Incidentally discovered adrenal masses

THE finding of an adrenal mass in the course of abdominal computerized tomography (CT) performed for other reasons poses an increasingly common clinical problem. The prevalence of such incidentally recognized masses ranges from 0.6 to 1.3 percent.1 2 3 An autopsy study performed in conjunction with one study of CT scans revealed a 1.9 percent prevalence of cortical adenoma in patients for whom no evidence of endocrinopathy was recorded during life.2 In addition, a single pheochromocytoma was found (prevalence, 0.1 percent). Another autopsy study found an 8.7 percent prevalence of adrenocortical adenoma.4 These data suggest that as scanning techniques continue to improve, . . .

Hormonal evaluation of the patient with an incidentally discovered adrenal mass.

Hormonal and morphological data were investigated in 202 consecutive patients with adrenal incidentalomas (171 unilateral and 31 bilateral) in an attempt to assess subclinical hyperfunction or malignancy. In addition to the classical evaluation, scintiscan was carried out in a large number of these patients. In unilateral incidentalomas, 83% showed normal hormonal function, whereas 17% had biochemical signs of adrenal overactivity (hyperaldosteronism in 3, hypercortisolism in 17, medullary hyperfunction in 9). [75Se]Methylnorcholesterol scintigraphy depicted malignant, space-occupying lesions as decreased or absent radiotracer uptake by the mass, and cortical adenomas as increased or normal uptake. In cortical adenomas a relationship between radiocholesterol uptake and degree of functional autonomy was demonstrated. [123I]Metaiodobenzilguanidine scintiscan visualized 7 of 8 pheochromocytomas. In bilateral incidentalomas, abnormal adrenal function was more frequent, accounting for 29% of cases (hyperaldost...

Incidentally discovered adrenal tumors : Endocrine and scintigraphic correlates

Objective: To determine the frequency of subclinical hormone secretion in incidentally discovered adrenal masses. Design: We reviewed the radiologic reports of 1779 consecutive computed tomographic scans of the chest, abdomen, and pelvis. Setting: Regional referral medical center. Patients: Eighty-nine patients with abnormalities of one or both adrenal glands were identified. Patients with non—adrenal gland malignant neoplasms, primary aldosteronism, adrenal hemorrhage, and death or severe illness were not investigated. The final study group consisted of 26 patients with incidentally discovered adrenal masses. Main Outcome Measures: Aldosterone secretion was assessed by measuring plasma renin activity and the plasma aldosterone concentration in patients with unexplained hypokalemia. We evaluated cortisol secretion by performing a 1-mg overnight dexamethasone suppression test and by measuring the corticotropin concentration at 8 AM by a sensitive method. In patients with low corticotropin values, we also measured the 24-hour urinary excretion of free cortisol and 17-ketosteroids and assessed diurnal variation by measuring plasma cortisol concentrations at 8 AM and 4 PM. Adrenal medullary function was studied by measuring urinary free catecholamines. Results: One patient had unrecognized primary aldosteronism, two patients had elevated free catecholamine excretion, and three patients (12%) had subclinical Cushing's syndrome. Conclusion: Based on our observations and a review of the literature, we conclude that subclinical hormone secretion, especially cortisol secretion, is more common in patients with incidentally discovered adrenal masses than previously appreciated. Surgeons and anesthesiologists must be alert to the possibility that adrenal insufficiency or a hypertensive crisis may develop in the perioperative period in patients with incidentally discovered adrenal masses. (Arch Surg. 1994;129:291-296)

Subclinical hormone secretion by incidentally discovered adrenal masses.

Subclinical hypercortisolism (SH) is a newly characterized hormonal disorder that is almost exclusively detected in the context of incidentally discovered adrenal masses. The diagnostic criteria used for the definition of this condition are at present controversial. Amongst the various tests used for the detection of this abnormality (dexamethasone suppression, urinary free cortisol, ACTH levels, midnight serum or salivary cortisol concentrations, ACTH responses to CRH stimulation), the dexamethasone suppression tests (DST) seem to better accomplish the task of unmasking subtle abnormalities of cortisol secretion. Several versions of DST have been used: the 1-mg overnight, the 3-mg overnight and the classical 2-day low-dose DST. This latter test has the theoretical advantage that, by more efficiently suppressing pituitary ACTH secretion, it may provide a measure of the residual (ie non- ACTH-dependent) cortisol secretion from the adrenal mass. In this way, post-dexamethasone cortisol concentrations may quantify the degree of autonomous cortisol hypersecretion. In fact, post-dexamethasone cortisol concentrations have a negative correlation with basal ACTH levels and a positive correlation with midnight cortisol concentrations as well as the size of the incidentally discovered adrenal mass. Most of the existing data indicate that SH detected in the context of adrenal incidentalomas may have some clinically significant implications. In fact, patients with higher post-dexamethasone cortisol concentrations demonstrate higher lipid levels and lower bone mass densities. It has also been suggested that SH may be responsible for biochemical and phenotypic changes reminiscent of the metabolic syndrome. In summary, SH does exist and is associated with a negative impact in patients' health; however, hormonal cut-off criteria for decision-making remain to be defined.

Endogenous subclinical hypercortisolism: Diagnostic uncertainties and clinical implications

Seven patients with unilateral and one patient with bilateral and asymmetric (R greater than L) incidentally discovered adrenal mass abnormalities depicted by computed tomography (CT) were studied by 131I-6 beta-iodomethyl-19-norcholesterol (NP-59) scintigraphy. There was marked lateralization of NP-59 uptake to the side of the mass lesion in the seven patients with unilateral masses and prominent asymmetric, (R greater than L) bilateral uptake in the patient with bilateral masses despite the fact that there were no obvious abnormalities of adrenocortical or adrenomedullary function as determined from peripheral blood and 24-hr urinary hormone measurements. Simultaneous bilateral adrenal vein catheterization (AVC) was employed to measure the levels of hormone effluent from the adrenal cortex and medulla and in all instances the cortisol concentrations were greatest from the side of the mass lesion in those patients with unilateral masses and from the larger of the two adrenals in the patient with bilateral adrenal masses. Thus, there was congruence between the anatomic (CT) and functional (NP-59 scintigraphy and AVC) investigations that depicted asymmetry of the adrenal glands which were not associated with abnormalities of overall adrenal function or hypothalamic-pituitary-adrenal axis integrity.

R. J. Grekin

Papers

Functional and scintigraphic evaluation of the silent adrenal mass