880 FIG. 1. Preoperative computed tomography (CT) images of left adrenal tumors (arrows). We did not identify the presence of fat in the tumors (A). The tumors showed the same dynamic contrast enhancement pattern as the right renal tumor (B, C). Korean J Urol 2010;51:879-881 Ishida et al sions had been pointed out during the patient’s past peri- odic checkups, including CT and US. Consequently, we clinically diagnosed right RCC and left adrenal metas- tases. Before the operation, 123I-MIBG scintigraphy re- vealed no uptake in the left adrenal region and we ruled out pheochromocytoma. Later, we performed right neph- rectomy and left adrenalectomy. Macroscopically, the size of the right renal tumor was about 50x45 mm and the sizes of the left adrenal tumors were 18x15 mm and 15x10 mm (Fig. 3). All were yellowish-white tumors. Pathological ex- amination revealed that the tumor form was alveolar growth and there were many atypical cells that were com- posed of swelling nuclei in the clear cytoplasm. The tumor was diagnosed as RCC of the clear cell type (Fig. 4). Right renal venous invasion was also identified, but there was no lymphoid invasion. The pathological diagnosis of the re- sected left adrenal tumors was also RCC. Since the oper- ation, the patient has been in good health without any re- currence for 12 months. DISCUSSION About 25% of patients with RCC show evidence of meta- stasis at the time of presentation [5,6]. The lungs, bone, lymph node, and liver are the major sites of metastatic spread [1]. It is said that the adrenal gland is the fifth organ to be metastasized [7]. Malignant involvement of the ipsi- lateral adrenal gland is noted in only 1.2% to 10% of cases [8,9]. Moreover, contralateral adrenal involvement by RCC is extremely rare. To study the frequency of meta- stasis in patients with RCC, Saitoh et al conducted autops- ies in 1,828 patients [2]. They reported that solitary and synchronous contralateral adrenal metastases were seen in 0.19% of the patients [2]. In 2003, Lau et al described that the type of RCC that metastasized to the contralateral adrenal gland was only the clear cell type [1]. The biological mechanism of adrenal metastasis from contralateral RCC is not clear. Contralateral adrenal metastasis of RCC is thought to occur via the hematogeneous route, as is the case for other organ metastases. Some studies reported that the adrenal gland was suggested to have a higher affinity for the spread of RCC than other organs because contralateral FIG. 2. Preoperative contrast-enhan- ced CT images of the right renal tu- mor. The tumor was heterogeneously enhanced, and the degree of enhance- ment was weaker than the normal renal parenchyma in the early phase (A). The tumor showed mild wash-out in the delayed phase (B). We also found right renal venous invasion (A).