Two-year follow-up of thirty-two non-functional benign adrenal incidentalomas.

OBJECTIVE: To evaluate the risk of developing endocrine hyperactivity and carcinoma during a period of up to 5 yr in patients with apparently benign and non-functioning adrenal incidentalomas. PATIENTS AND METHODS: Thirty-two patients (mean age: 57.0+/-8.3 yr) were investigated in a prospective follow-up study for a median time of 24 months. Twenty-eight patients had unilateral and 4 had bilateral masses. Initial average mass diameter was 17.47+/-6.60 mm. All patients were followed up yearly by physical examination, metabolic parameters, hormonal evaluation [morning cortisol after 3-mg dexamethasone suppression, urinary metanephrines, and upright aldosterone/ plasma renin activity (PRA)].
RESULTS: Among the clinical characteristics, 48% of patients were obese, 20% were hypertensive, 13 had Type 2 diabetes and impaired glucose tolerance. During follow-up period no significant change in the functional status was observed and nomalignant transformation occurred. Only 1 patient developed subclinical Cushing's syndrome at the end of the 1st year and referred to surgery. Change in mass size was correlated with homeostasis model assessment of insulin resistance (p=0.002), upright aldosterone/ PRA (p=0.041), cortisol after dexamethasone suppression (p=0.048) and 24-h urinary normetanephrine (p=0.005) levels. Gender, body mass index, glucose metabolism, and blood pressure were not found to be correlated with change in mass size and functional status.
CONCLUSIONS: Due to the extremely low risk of developing malignancy during up to 5 yr of follow-up, conservative approach for the management of adrenal incidentalomas is thought to be appropriate. However, possibility of evolution to hormonal hypersecretion makes long-term follow-up of 2-to-5 yr seems to be obligatory.