Scintigraphy of incidentally discovered bilateral adrenal masses

The purpose of this study was to determine the patterns of iodine-131 6β-iodomethylnorcholesterol (NP-59) imaging and the correlation with CT-guided adrenal biopsy and follow-up in patients with bilateral adrenal masses. To this end we investigated a consecutive sample of 29 euadrenal patients with bilateral adrenal masses discovered on CT for reasons other than suspected adrenal disease. Adrenal scintigraphy was performed using 1 mCi of NP-59 injected i.v., with gamma camera imaging 5-7 d later. In 13 of the 29 patients bilateral adrenal masses were the result of metastatic involvement from lung carcinoma (5), lymphoma (3), adrenocarcinoma of the colon (3), squamous cell carcinoma of the larynx (1), and anaplastic carcinoma of unknown primary (1). Among these cases the NP-59 scan demonstrated either bilaterally absent tracer accumulation (8, all with bilateral metastases) or marked asymmetry of adrenocortical NP-59 uptake (5). Biopsy of the adrenal demonstrating the least NP-59 uptake documented malignant involvement of that gland in five of five patients. In two patients an adenoma was found simultaneously in one adrenal with a contralateral malignant adrenal mass. In each of these cases, the adenoma demonstrated the greatest NP-59 uptake. In 16 patients diagnosis of adenoma was made on the basis of CT-guided adrenal biopsy of the gland with the greatest NP-59 uptake of the pair (n=4), or adrenalectomy (n=2), or absence of change in the size of the adrenal mass on follow-up CT scanning performed 6 months to 3 years later (n=10). (orig./MG)