[Adrenocortical scintigraphy to evaluate incidental adrenal mass (incidentaloma) discovered on computed tomography]

To assess the nature of adrenal mass incidentally discovered on computed tomography, adrenocortical scintigraphy with I-131-6 beta-iodomethyl-19-norcholest-5(10)-en-3 beta-ol (I-131 Adosterol) in 29 patients was retrospectively reviewed. All patients had no clinical symptoms and biochemical evidence of adrenal hyperfunction. Six of them had extra-adrenal malignancy. Increased tracer uptake on the side of adrenal mass was observed in 13 patients (concordant group): cortical adenoma in 8, macronodular hyperplasia in 1, no growing tumor in 1, and no further examination in the remaining 3 patients. No cancer patients were included in the concordant group. Symmetric uptake was seen in 9 patients (symmetric group): 1 cortical adenoma and 1 ganglioneuroma, 6 no growing tumor (two of them had malignancy), and no further examination in 1 patient. Decreased uptake were shown in 7 patients (dis-concordant group): metastasis in 4, adrenal cyst in 2, and no growing tumor in 1. Adrenocortical scintigraphy was helpful in distinguishing benign functioning adrenal masses from non-functioning adrenal masses such as metastatic tumor and cyst.