Clinical Study of Adrenal Incidentaloma in Korea

BACKGROUND: This study was designed to evaluate the clinical, endocrinological and histological characteristics of adrenal incidentalomas. METHODS: Eighty patients (41, males; 38, females; age range 17-80 years) who were diagnosed with adrenal incidentaloma at Korea University Hospital from 1992 to 2003 were studied retrospectively. RESULTS: Endocrinological investigation revealed 16 pheochromocytomas (20%), nine Cushing's syndromes (11%), eight primary aldosteronism (10%) and 46 non-functioning tumors (58%). Forty-four patients received operations, and biopsies were performed on two patients. Pathologic examination revealed 16 adrenocortical adenomas (20%), five carcinomas (6%), 13 pheochromocytomas (16%), three metastatic cancers (4%), and other tumors (10%). The diameter of the carcinomas (mean: 10.8 cm, range: 5-19 cm) were significantly larger than the diameter of benign adenomas (mean: 2.84 cm, range: 1-6 cm) (p=0.002). According to the receiver operating charactenstic (ROC) curve analysis, the cut-off value of tumor size for discriminate malignant tumor was 4.75 cm (sensitivity 90%, specificity 58%). Twenty-four patients with non-functioning tumors were followed up for a period of 3 to 72 months. During the follow up period, two patients showed an increase in tumor size of more than 1 cm, and one patient developed Cushing's syndrome. Changes in mass size and function were observed only between 10 and 26 months after the initial diagnosis. CONCLUSIONS: These data show that an endocrine evaluation should be performed in all adrenal incidentalomas, and an adrenalectomy is recommended for tumors 5 cm or greater or tumors with adrenocortical hyperfunction. In addition, these tumors should be monitored for changes in mass size and function for a follow up period of approximately 26 months.