Management of incidentally discovered adrenal masses and risk of malignancy

Incidentally discovered adrenal masses of more than 1 cm in size are relatively frequent, but the correct management of such lesions is not well established.

Between 1980 and 1999, 158 patients (73 men [46.2%] and 85 women [53.8%]; median age, 58 years) with adrenal incidentalomas of more than 2 cm in size were observed. Sixty-eight patients (43.0%) underwent adrenalectomy. The main reasons for surgery were (1) suspicious computed tomography (CT) scan or magnetic resonance imaging (MRI) appearance or no uptake at the 75-Se-norcholesterol scintigraphy (NCS; n = 22 patients), (2) an increase in the size of the mass of more than l cm (n = 15 patients), (3) subclinical endocrine hyperfunction (n = 14 patients), and (4) mass size of more than 5 cm (n = 22 patients), with imaging-guided fine-needle aspiration biopsy with spinal-type narrow-gauge needle (FNAB) that suggested malignancy (n = 5 patients).

Pathologic examination showed 39 adrenocortical adenomas (57.4%), 20 adrenal malignancies (29.4%; carcinomas, 15; unsuspected metastases, 3; nonfunctioning malignant pheochromocytomas, 2), and 9 various benign lesions (13.2%). All masses that increased in size were benign. Seven malignant tumors (46.7%) were 3 to 4 cm in size, and 14 benign lesions (29.1%) were 5 to 6 cm in size. Sensitivity and specificity in the detection of malignancy were 100% and 100% for NCS (n = 34 patients) and FNAB (n = 19 patients), 75.0% and 93.7% for CT scan (n = 68 patients), and 87.5% and 100% for MRI (n = 26 patients), respectively.

To differentiate benign and malignant incidentalomas, NCS and FNAB are more sensitive than CT scan and MRI; size criteria are of little value.