Radiological and functional analysis of a cohort of adrenal adenomas

Abstract

AIM: A cohort of adrenal incidentalomas which had radiological or histological characteristics in keeping with an adrenal adenoma was analysed in terms of the radiological and functional characteristics.

METHODS: A retrospective cross-sectional analysis of a cohort of adrenal adenomas was carried out. Lesions were followed up for a median of 8.2months (IQR 1.4–34.6). In the majority of patients (69.95%), the diagnosis of a benign adrenal adenoma was made via an unenhanced CT scan (density of lesion <10HU in keeping with a lipid rich adenoma). In those patients where the adrenal lesion was lipid poor (density >10HU on an unenhanced CT scan) or had a contrast scan in the first instance, the absolute or relative washouts were calculated in 11.0% and 13.5% respectively. MRI was the imaging modality of choice in 1 patient. 3 patients had an adrenalectomy, with histology confirming an adrenocortical adenoma.

RESULTS: 209 patients with adrenal adenomas were included. Out of the whole cohort, 111 patients were females (53.1%). The mean age of patients at diagnosis was 62.3 years (± 12.1SD). Left sided lesions were noted to be the commoner lesions, being present in 61.2% and bilateral lesions in 6.2%. The median longest radiological diameter (on CT or MRI) was 19.0 mm (IQR15.0–25.0). During this follow up period, practically no change in size of the adenomas was identified (median change in size 0 mm (IQR 0–1).

Morning cortisol following 1mg overnight dexamethasone suppression was >50 nmol/l in 34.2% in keeping with possible autonomous cortisol secretion. 4 out of these patients had cortisol above 138nmol/l in keeping with autonomous cortisol secretion. 0900 h cortisol post ODST correlated positively with age (P = 0.003) and longest radiological diameter of adenoma (P < 0.001) and negatively with DHEAS (P < 0.001). Multiple logistic regression analysis maintained the positive correlation between 9am post ODST cortisol with age (OR 1.066 P = 0.004) and longest radiological tumour diameter (OR 1.168 P < 0.001).

A high aldosterone renin ratio was found in 36% of patients. Out of these patients, 22% also had a level of cortisol following overnight dexamethasone suppression of more than 50 nmol/l.

CONCLUSION: Interesting correlations between biochemical and radiological parameters in patients with adrenal adenomas have been established. The correlation between 0900 h cortisol following the overnight dexamethasone suppression test and age is not documented in the literature.