A case of renal juxtaglomerular cell tumor that was preoperatively diagnosed by selective renal venous sampling

A 26-year-old woman without a family history of hypertension was referred to our hospital for a further examination of juvenile hypertension. At 25 years of age, she had headaches, and hypertension (210/120 mmHg) was first noted. A diagnostic examination to assess the hypertension was performed and she was hypokalemic with serum K 2.9 mEq/L. Moreover, the plasma renin activity (PRA) and plasma renin concentration (PRC) was markedly elevated (18.7 ng/mL/h and 196.3 pg/mL), and plasma aldosterone concentration (PAC) was also elevated (291 pg/mL). A captopril challenge test showed a mildly increased PRA response (15.5 ng/mL/h to 20.3 ng/mL/h), but MR angiography and renogram showed no findings suggestive of renal vascular hypertension. On the other hand, dynamic contrast-enhanced CT showed a small neoplastic lesion (10 mm in diameter) without enhancement in the early phase, but with slight enhancement in the late phase, on the left renal upper pole. We performed renal vein sampling, but no obvious lateralization in PRA was found at the main trunk level of the left and right renal veins (14.0 vs. 14.3 ng/mL/h). Therefore, we performed more selective sampling of the branches of the left renal vein and found that PRA in the upper pole branch of the left renal vein was approximately 3.7 times higher than in the inferior pole branch, the main trunk of the left and right renal veins, and the inferior vena cava (51.5 ng/mL/h vs. 14.0–15.1 ng/mL/h). Based on these results, we made a preoperative diagnosis that the tumor in the upper pole of the left kidney was a juxtaglomerular cell tumor producing renin excessively and decided to perform partial left nephrectomy. Juxtaglomerular cell tumors (JCT) are very rare diseases that primarily occur in adolescents and young adults. Excessive renin secretion from the tumor causes secondary hypertension, and hypokalemia. It has been reported that renal vein sampling, in addition to CT and MRI scans, is useful for preoperative localization of JCT. However, the usual method of sampling only the main trunk of the renal vein fails to detect lateralization of the PRAs in many cases. In the present case, we were able to identify the localization of the tumor by performing sampling of the branches of the renal vein. We herein report on the usefulness of selective renal vein sampling for the preoperative diagnosis of JCT.