Characteristics of adrenal incidentalomas: a single-centre audit

Abstract

Introduction: Adrenal incidentalomas are commonly encountered due to increasing utility and sensitivity of imaging. We reviewed the characteristics and outcome of adrenal incidentalomas followed up in a single centre. Methods: We retrospectively reviewed patients with adrenal incidentaloma referred to the endocrine clinic at Queen Mary Hospital, Hong Kong, between June 2012 and May 2015. We excluded cases where index imaging was done for suspected adrenal disorders, staging, or follow-up for malignancies, or where clinical features of endocrine disorders were missed due to superficial assessment. All patients were evaluated and followed up according to a standard protocol. Results: Among 75 patients included (57.3% men, 42.7% women), 68 had unilateral lesions and seven had bilateral lesions. The majority of patients were aged 60 to 69 years. In all, 14.7% of patients had adrenal incidentalomas of initial size <1.0 cm, 60% had 1.0 to 2.0 cm, 22.7% had 2.1 to 3.9 cm, and 2.7% had ≥4 cm. Hormonal evaluations showed 50% of lesions were non-functional, 35% showed subclinical Cushing’s syndrome, 12% showed primary aldosteronism, and 3% showed catecholamine oversecretion. Eleven patients underwent adrenalectomy: eight for adrenocortical adenoma with autonomous cortisol secretion, two for phaeochromocytoma, and one for adrenocortical carcinoma. In addition, 64 patients were managed nonoperatively; 59 patients underwent reassessment imaging. Two showed complete resolution, 54 showed no interval growth over a median of 31.5 months (interquartile range 24-46.75 months). Three patients showed cumulative interval growth ≥5 mm from baseline: one remained under regular imaging surveillance, but the other two were lost to follow-up. Hormonal surveillance was performed in 11 initially non-functioning lesions; the majority were to reassess autonomous cortisol secretion, which did not alter management. Conclusion: Hormonal evaluations should be performed for adrenal incidentalomas regardless of size. Subclinical Cushing’s syndrome was the most common hormonal abnormality. Surgical intervention for subclinical Cushing’s syndrome remains controversial among clinicians; co-morbidities associated with autonomous cortisol secretion should be monitored. Reassessment of dedicated adrenal imaging is necessary to ensure no interval change in size. Hormonal surveillance did not alter the management of initially benign non-functioning adrenal incidentalomas in our series.