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

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.

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)].

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.

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.