Importance of adrenal incidentaloma in patients with a history of malignancy

Background. Adrenal incidentaloma presents a frequent finding inpatients with a history of malignancy. This study was carried out to determine whether imaging techniques can discriminate between a malignant and a benign adrenal tumor and subsequently select candidates for adrenal surgery. Methods. Beginning in July 1995, oncologic patients with adrenal incidentaloma underwent abdominal ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and [(18)]fluoro-2-deoxy-D-glucose Positron emission tomography (18-FDG-PET). Consecutively in all patients adrenalectomy was performed. Histologic findings were compared with the imaging results. Results. In 42 patients, 33 to 79 years old (mean age, 58 years), 44 adrenal lesions were detectable. Two patients presented with bilateral adrenal masses. At operation, 43 adrenal resections and 3 biopsies were performed. Histologic examination revealed 31 metastases (71%) and 13 adrenal adenomas (29%). In metastases the sensitivity of ultrasonography, CT, MRI, and 18-FDG-PET was 66%, 81%, 100 and 100%, respectively. for adrenal adenoma, the sensitivity of ultrasonography, CT, MRI, and 18-FDG-PET was 46%, 39%, 100%, and 54 %, respectively. Conclusions. In oncologic patients with indeterminate adrenal tumors MRI and 18-FDG-PET provide accurate differentiation between metastases and benign adenomas. Positive results of these 2 imaging modalities are highly suggestive for metastatic disease. In cases of negative MRI and 18-TDG-PET results the adrenal lesion corresponds to a benign adenoma that needs no surgical intervention.