Long-Term Follow-Up of Adrenal Incidentalomas: A Portuguese Single-Center Study

Introduction: Adrenal incidentalomas are asymptomatic adrenal masses detected incidentally during imaging. Their prevalence ranges from 1 to 8%, increasing with age. Despite current guidelines recommending minimal follow-up for lesions <1 cm, approximately 15-30% of incidentalomas may be hormonally active. This study aimed to evaluate tumor growth and hormone secretion in nonfunctioning adrenal incidentalomas over a long-term follow-up. Methods: Retrospective cohort study at the Endocrinology Department of Hospital das For & ccedil;as Armadas, Portugal, evaluating patients with adrenal incidentalomas over a median follow-up of 7 years. The study included patients over 18 years with adrenal incidentalomas and at least 5 years of follow-up. Patients underwent computerized tomography to assess tumor size and density. Hormonal evaluations included the 1-mg overnight dexamethasone suppression test, urinary fractionated metanephrines, and plasma aldosterone and renin activity. Results: A total of 136 patients, with a median age of 74 years, were evaluated. The median tumor size at diagnosis was 20 mm. Most tumors (81.6%) remained stable in size, density, and homogeneity. Significant tumor growth was observed in 11% of patients, primarily associated with heterogeneous appearance. Nine patients had autonomous cortisol secretion at baseline, without developing overt Cushing's syndrome during follow-up. No new cases of hormone hypersecretion were observed. Conclusion: Our study supports the existing guidelines that benign adrenal incidentalomas generally exhibit stability over time, with a low risk of malignant transformation or significant hormonal activity. Comprehensive initial evaluation is crucial, but further radiologic follow-up is often unnecessary. We recommend adherence to European Society of Endocrinology and European Network for the Study of Adrenal Tumors guidelines, focusing on individualized patient management.