Adrenal incidentalomas in Taiwan: High prevalence and malignancy rate

Background: The endocrine adrenal gland has 3 zones comprised of the cortex and medulla. The character of multi-hormonal expression results in multiple clinical manifestations. To define the clinical characteristics of adrenal tumors in Taiwan, we reviewed 336 pathologically proven adrenal tumors at Chang Gung Memorial Hospital in Linkou. Methods: We retrospectively analyzed 258 pathologically proven adrenal tumors with sufficient data treated from 1983 to 2000. Among them, 174 (67%) were functional and 84 (33%) were nonfunctional. The diagnosis was based on clinical features, hormonal status, imaging studies, and pathology. Results: Of the 258 patients, 161 were women (mean age, 38.5±15.4; range, 1-75 years) and 97 men (mean age, 41.6±17.8; range, 1-81 years). The prevalence of cortical tumors was much higher in females than in males. Fifty-two percent of patients with an adrenal tumor were diagnosed at an age between 30 and 50 years. Incidentalomas (N=84) accounted for about 1/3 of total tumor cases. Of the 46 cases proven to be malignant, 40 (87%) were found incidentally. All malignant tumors had a diameter of greater than 3 cm. Postoperative adrenal insufficiency was present in 18% of cases, and overall mortality in this study was 0.4%. Conclusions: In our series, adrenal incidentalomas corresponded to about 1/3 of adrenal tumors and accounted for 87% of malignancies. It is mandatory to increase medical attention for incidentally found adrenal masses in Taiwan. Those incidentalomas with a diameter of more than 3 cm should undergo a pathological examination.