The role of adrenocortical scintigraphy in the evaluation of unilateral incidentally discovered adrenal and juxtaadrenal masses

A black adrenal adenoma difficult to be differentiated from a malignant adrenal tumor by CT, MRI, scintigraphy and FDG PET/CT examinations

Black adrenal adenoma (BAA) is an adrenal adenoma which contains lipofuscin and has a black or brown appearance. Preoperative diagnosis of BAA is difficult because it is diagnosed by pathologic findings. We report a case of an incidentally discovered non-hyperfunctioning BAA in the left adrenal gland of a 58-year-old man. It showed an oval lipid-poor mass, 3 cm × 2 cm in size on computed tomography (CT) and magnetic resonance imaging (MRI), no avid uptake of (131)I-norcholesterol and (123)I-meta-iodobenzylguanidine (MIBG) on scintigraphy, and intense avid uptake of (18)F-fluorodeoxyglucose (FDG) on positron emission tomography-CT (PET/CT). FDG PET/CT showed that it was a hypermetabolic lesion, more intense than the activity of the liver, and the maximum standardized uptake value was 5.6 on 1-h early imaging and 8.3 on 2-h delayed imaging, suggesting a malignant tumor. BAA is a clinically rare benign adrenal adenoma, but it should be kept in mind that BAA may exhibit false-positive results for malignancy or inconclusive results for benignity with modern imaging modalities including CT, MRI, adrenal scintigraphy with radiolabelled cholesterol and radiolabelled MIBG, and FDG-PET like this case.

ACR Appropriateness Criteria on incidentally discovered adrenal mass

For patients without a history of malignancy, most small (less than 3 cm) incidentally discovered adrenal masses are benign, and extensive and costly workup is usually not justified. For incidentalomas from 3 to 5 cm in size, computed tomography, magnetic resonance imaging, 2-[(18)F]fluoro-2-deoxyglucose positron emission tomography, adrenal biopsy, or surgery can be considered. Lesions larger than 5 cm should be removed because of the higher risk for malignancy. For patients with histories of malignancy, incidentally discovered adrenal masses are more often malignant, and thus even smaller adrenal lesions are suspect. Adrenal biopsy should be reserved for cases in which the results of noninvasive techniques are equivocal.

[Adrenocortical secretory tumors]

Adrenocortical tumors are rare and mostly non-secreting; their discovery is incidental. When secreting, they produce steroid excess and result in a clinical presentation such as the Cushing syndrome, primary aldosteronism, virilization or feminization syndrome. Such tumors are mostly sporadic but can belong to hereditary syndromes predisposing to tumors. The diagnosis of secreting adrenocortical tumors is based upon clinical presentation and biological data associated with specific biological assessments. Adrenal imaging has been considerably improved with the development of CT scan, which can be completed by MRI if necessary. Most of adrenocortical tumors are adenoma, nevertheless some of them can be malignant and the prognosis of such carcinomas is poor. Management of secreting adrenocortical tumors requires surgery in most of the cases and laparoscopic access is now widely used and provides good results in the treatment of benign tumors.

The clinically inapparent adrenal mass: update in diagnosis and management

Clinically inapparent adrenal masses are incidentally detected after imaging studies conducted for reasons other than the evaluation of the adrenal glands. They have frequently been referred to as adrenal incidentalomas. In preparation for a National Institutes of Health State-of-the-Science Conference on this topic, extensive literature research, including Medline, BIOSIS, and Embase between 1966 and July 2002, as well as references of published metaanalyses and selected review articles identified more than 5400 citations. Based on 699 articles that were retrieved for further examination, we provide a comprehensive update of the diagnostic and therapeutic approaches focusing on endocrine and radiological features as well as surgical options. In addition, we present recent developments in the discovery of tumor markers, endocrine testing for subclinical disease including autonomous glucocorticoid hypersecretion and silent pheochromocytoma, novel imaging techniques, and minimally invasive surgery. Based on the statements of the conference, the available literature, and ongoing studies, our aim is to provide practical recommendations for the management of this common entity and to highlight areas for future studies and research.

Diseases of the adrenal gland

It is fortunate that the ability to diagnose the specific adrenal entities that mandate a surgical approach is extremely accurate. The combination of analytic methodology to measure the appropriate adrenocortical and medullary hormonal production and the radiologic techniques for localization are superb. The management of these adrenal disorders usually using a laparoscopic approach following localization is highly successful, resulting in a reversal of both metabolic abnormalities and the hypertension that often accompanies these diseases. Indeed, this is a true success story with the evolution of these different techniques over the past 50 years.

Adrenal incidentalomas showing unilateral concordant visualization by adrenocortical scintigraphy: comparison with adenomas in Cushing's syndrome

An adrenocortical adenoma causing Cushing's syndrome (Cushing's adenoma) produces a unilateral concordant visualization (UCV) imaging pattern in which the adenoma is only visualized on radioiodocholesterol adrenocortical scintigraphy. But because this imaging pattern is also noted in some patients with adrenal incidentalomas, we examined whether the UCV-incidentaloma was essentially identical with Cushing's adenoma and would develop Cushing's syndrome. The subjects were 9 patients with UCV-incidentalomas (mean size, 30 mm; range, 20-45 mm) and 6 patients with Cushing's adenomas (mean size, 28 mm; range, 25-35 mm). Endocrinological evaluations showed several abnormalities including blunted diurnal rhythm of plasma cortisol within the normal range, low plasma ACTH and/or high 24-hr urinary 17-OHCS levels in 8 of 9 patients with UCV-incidentalomas, but these abnormalities did not meet the diagnostic criteria of Cushing's syndrome. Adrenal uptake of the tracer in the patients with UCV-incidentalomas was not statistically different from that in the patients with Cushing's adenomas and had no relationship with hormonal values in either patient group. Tumor size on CT correlated with the levels of 24-hr urinary 17-OHCS (r = 0.75, p = 0.02) and plasma cortisol at 7:00 (r = 0.82, p = 0.007) in the patients with UCV-incidentalomas, but not in the patients with Cushing's adenomas. Although 3 UCV-incidentalomas increased slightly in size, none of 9 patients with UCV-incidentalomas has developed Cushing's syndrome for 4 to 52 months. These results suggest that the UCV-incidentaloma may be essentially different from the Cushing's adenoma and unlikely to develop Cushing's syndrome.

Reduced serum levels of dehydroepiandrosterone sulphate in adrenal incidentalomas: a marker of adrenocortical tumour

BACKGROUND AND OBJECTIVE

Reduced serum levels of dehydroepiandrosterone sulphate (DHEAS) have been shown in patients with Cushing's syndrome resulting from adrenocortical adenoma, in contrast with normal DHEAS levels in patients with Cushing's disease. The aim of this study was to verify whether patients with incidentally discovered adrenocortical adenomas also have reduced levels of DHEAS.

DESIGN

Evaluation of serum DHEAS, serum and urinary cortisol, plasma ACTH and low dose dexamethasone suppression test in patients with adrenal incidentaloma and Cushing's syndrome.

PATIENTS

Thirty-two patients with adrenal incidentaloma and, as controls, 17 patients with overt Cushing's syndrome, were studied.

RESULTS

Serum DHEAS levels lower than normal were found in 21/24 (87.5%) patients with adrenocortical incidentaloma, but in only 1/8 patients with a mass of non-adrenocortical origin. This patient had massive bilateral metastatic infiltration of both adrenal glands and primary adrenal failure. The prevalence of low DHEAS levels in the two groups was significantly different (P = 0.0001). In patients with adrenocortical incidentaloma, the prevalence of low DHEAS levels was significantly higher (P = 0.0001) than that found for some hormonal alterations indicating pre-clinical hypercortisolism (high urinary cortisol, unsuppressed serum cortisol after low dose dexamethasone administration and low plasma ACTH). Low DHEAS levels were found in all patients with Cushing's syndrome due to adrenocortical adenoma but in none of those with Cushing's disease.

CONCLUSIONS

Our results indicate that the finding of low DHEAS levels can be considered a marker of the adrenocortical origin of an adrenal incidentaloma, provided adrenal failure has been excluded.