Asymptomatic adrenal tumor; 386 cases in Japan including our 7 cases.

To clarify the indication of surgery in incidentally discovered asymptomatic adrenal masses, we analyzed 386 Japanese cases, 379 cases reported in Japan during the past 25 years (from 1964 to 1988) and 7 cases from our own experience. From a total of 460 patients, we carefully selected 379 patients satisfying our criterion of the absence of symptoms and signs suggestive of active hormone over-secretion as described in each case report. From the Japanese series, there was a high incidence of pheochromocytoma patients (20 of 37 patients) who had no symptoms and signs but had high plasma or urine catecholamines. Scintigraphy with 131I-meta-iodo-benzyl-guanidine was useful in the diagnosis of pheochromocytoma. For the other asymptomatic adrenal tumors, except for myelolipoma and adrenal cyst, differential diagnosis between malignant and benign adrenal lesions by imaging procedures such as whole body computed tomography (CT), ultrasonography (US), adrenocortical scintigraphy, and angiography was not always possible. In addition, among the 109 patients with cortical tumors whose hormonal data were reported, no clear-cut differentiation of malignant tumor from benign by means of these data could be obtained. Since 1980 whole body CT scanner and high resolution US scanner have become widely available, and there have been 283 cases of asymptomatic adrenal tumors who satisfied our criterion. Cortical carcinomas smaller than 3 cm and 6 cm in diameter account for 3.8% and 6.6%, respectively, of the total of 101 cases of cortical carcinoma, cortical adenoma, ganglioneuroma, and hemangioma during this period. The size of the smallest cortical carcinoma with metastasis was 2 cm in diameter in this series. Pre-operatively, an adrenocortical carcinoma 2.8 cm in diameter in our patient could not be diagnosed as such by imaging techniques and measurement of plasma hormones. These findings suggest that an adrenal mass larger than 3 cm should be removed and a patient with a smaller cortical tumor should be carefully followed up.