[Adrenal incidentaloma]

Recent increased use of ultrasonography and computed tomography (CT) has detected a substantial number of incidentally discovered adrenal tumor (incidentaloma). In our institute the discovery rate of adrenal incidentaloma per number of abdominal CT examinations was 0.43%. Those incidentalomas were incidentally found during examination for abdominal discomfort and lumbar pains or evaluation of the cause of hypertension. In the group study by the research committee on "Disorders of Adrenal Steroid Hormones" under the sponsorship of the Ministry of Health and Welfare of Japan, in 53 of 149 patients with incidentaloma, surgical resection was done during 5 years between 1983 and 1989. The pathological examination of those tumors revealed 67.9% of non-hyperfunctioning adrenocortical adenoma, 9.4% of adrenal cancer, 9.4% of ganglioneuroma, 5.7% of pheochromocytoma, 5.7% of adrenal cyst and 1.9% of myelolipoma. The criteria for resection of adrenal incidentaloma have not been established. However, tumors having a diameter of over 5 cm are generally excised in most institutes. Tumors having a diameter of between 3 cm and 5 cm are usually resected if the shape of the tumor is ambiguous and the margin of the tumor is irregular. Tumors having a diameter of less than 3 cm should be carefully followed up by abdominal CT examination every 6 months.