Objective: To determine the clinical outcomes and follow-up imaging characteristics for incidentally discovered adrenal nodules at a large metropolitan health care center, as well as compliance with National Institutes of Health guidelines for the evaluation of these lesions.
Methods: Between October 2003 and June 2005, computed tomographic (CT) scanning performed at Harvard Vanguard Medical Associates detected 165 adrenal nodules (incidentalomas) in 129 patients without extra-adrenal malignant lesions or evidence of adrenal hyperfunction. Nodule characteristics, including size at baseline, change in size at follow-up, CT attenuation values, biochemical data, and clinical outcomes, were analyzed.
Results: Of the 165 adrenal incidentalomas, 96% were smaller than 4 cm. When attenuation values were determined, 65% were low (<10 Housfield units). Ninety-eight patients (76%) with 142 nodules (86% of all incidentalomas) had at least 1 follow-up CT scan. Of these 142 lesions, 20 (14%) changed significantly in size (grew or became smaller by 0.5 cm or more). Growth was detected within 12 months in 5 of the 7 lesions (71%) that grew. For 95% of patients, the adrenal nodule did not necessitate intervention, including change in medication or surgical treatment. Biochemical studies for adrenal hyperfunction were done in 39 of the overall 129 patients (30%), but in only 20 of 109 patients (18%) not seen by endocrinologists.
Conclusion: Most adrenal incidentalomas are benign, nonfunctional tumors. Growth typically occurs within 12 months after detection. Despite the 2002 National Institutes of Health guidelines, 82% of patients at our medical center with adrenal nodules who were not seen by endocrinologists did not have hormonal testing. More physician education about the evaluation of incidentalomas should be provided, and prospective studies to establish the appropriate duration of follow-up should be conducted.