Accumulation of iodine-131-iodocholesterol in renal cell carcinoma adrenal metastases.

Adrenocortical scintigraphy is a useful technique for differentiating between types of nonhyperfunctioning adrenal masses. Metastatic tumors do not normally accumulate radioiodocholesterol and show discordant uptake on scintigrams. We present two patients who showed accumulation of 131I-6beta-iodomethyl-19-norcholesterol (NP59) in the adrenal metastases from renal cell carcinoma. In one patient with bilateral adrenal metastases, accumulation in the primary tumor as well as adrenal metastases was demonstrated. The adrenal metastases in both patients were resected and were histologically proven to be metastases from clear-cell renal carcinoma. Accumulation of NP59 in metastatic adrenal tumors, although a very rare finding, suggests a pitfall in the differential diagnosis of adrenal cortical tumors.