A case of atypical reninoma with mild hypertension and normal plasma renin activity but elevated plasma renin concentration

Abstract

Background Reninoma is a rare, benign renal neoplasm. Typical clinical features include severe hypertension, secondary hyperaldosteronism, hypokalaemia and metabolic alkalosis caused by the overproduction of renin. Case presentation A 25-year-old lean Chinese woman with no family history of hypertension was hospitalized for stage 1 hypertension that gradually developed over two years. Endocrine investigation showed hyperreninemia without hyperaldosteronism and hypokalaemia. Interestingly, although the patient had an elevated plasma renin concentration (PRC), her plasma renin activity (PRA) was in the normal range. Abdominal contrast-enhanced computed tomography (CT) scanning revealed a solid, low-density, renal cortical mass with delayed enhancement. Selective renal vein sampling (SRVS) was performed, and a lateralization of the renin secretion from the left kidney was found. Enucleation of the tumour led to a rapid remission of hypertension and hyperreninemia. Based on pathological findings, the patient was diagnosed with reninoma. Immunohistochemical staining of the tumour was positive for Renin, CD34, Vimentin, and synaptophysin (Syn) and negative for somatostatin receptor 2 (SSTR2) and chromogranin A (CgA). Conclusions Reninoma can present as mild hypertension without hyperaldosteronism and hypokalaemia. The clinical features of reninoma may depend on the degree of activation of the renin-angiotensin-aldosterone system (RAAS). PRC should be incorporated in the differential diagnosis of secondary hypertension.

Diagnostic challenges in patients with reninomas and extrarenal renin‐producing tumours

“…Some reninomas display low enhancement compared to the renal parenchyma and can even be mistaken for a cyst, 22,23 possibly explained by local vasoconstrictor effect of angiotensin II and/or a lack of neovascular development within the tumour. 22,24 In other cases, mild contrast enhancement is seen, especially in the late phase of imaging, [25][26][27][28][29][30] as in our Cases 2 and 3. MRI can also be used to identify reninomas and is often preferred in younger patients.…”

“…[18F]FDG‐PET has sometimes been used to evaluate reninomas after CT and MRI have identified the tumour. The results have been varying, in some cases there was an increased uptake 23,25,33 whereas in others, no uptake was seen 22,32 . The mechanism behind the varying results is unclear.…”