Reninoma: an uncommon cause of Renin-mediated hypertension

Abstract

Reninoma (juxtaglomerular cell tumor) is a rare cause of renin-mediated hypertension. Reninomas are usually diagnosed in adolescents and young adults with occasional reports in younger children. Patients typically present with a long history of headaches leading to a diagnosis of severe hypertension that responds well to antihypertensive treatment targeting the renin-angiotensin-aldosterone system. The clue to clinical diagnosis is the presence of hypokalemia and metabolic alkalosis on the first blood sample drawn before any treatment is instituted. Elevated blood levels of renin and aldosterone confirm the clinical suspicion of renin-mediated hypertension. Diagnostic imaging is employed to identify the source of excessive renin production. While renal ultrasound can miss reninoma, contrast CT or magnetic resonance imaging of the kidneys are diagnostic modalities of choice leading to the correct diagnosis. Renal vein renin sampling with lateralization might help to identify the site of excessive renin production. Nephron-sparing surgery is curative with maintenance of normal blood pressure after discontinuation of antihypertensive medications in the majority of patients. In this paper, we present the case of reninoma in an adolescent girl emphasizing clinical presentation, diagnostic evaluation, and medical and surgical treatment of this rare tumor. We also discuss important points in the management of children presenting with renin-mediated hypertension.

Keywords: blood pressure; hypertension; juxtaglomerular cell tumor; kidney; renin; reninoma.

Figure 1

CT angiogram. A sagittal reformat through the left kidney shows a rounded 10 mm low-attenuation lesion projecting from the extreme periphery of the anterior renal margin, appearing subcapsular in position (arrow).

Figure 2

Renal vein renin sampling with lateralization. Demonstration of the differential hormone levels between the main renal veins and elevation above systemic hormone levels (all above the upper limit of normal) confirmed the left kidney tumor as a source of excessive renin production.

Figure 3

Laparoscopic wedge resection of reninoma. Dissection of the tumor with scissors (A) and the closure of the defect with interrupted mattress suture (B).

Figure 4

Histopathology of reninoma. (A) Hematoxylin & eosin, ×200 magnification. The arrows point to juxtaglomerular cell tumor (reninoma). An incomplete fibrous capsule (arrow bases) separates the tumor from normal kidney (the upper right-hand corner). (B) Hematoxylin & eosin, ×400 magnification. The tumor comprises a uniform population of round to polyhedral cells with granular, eosinophilic cytoplasm. The growth pattern is solid with edema and single cells. (C) CD34 immunoperoxidase stain, ×40 magnification. The tumor cells stain positive for CD34. Adjacent glomerular vasculature acts as an internal positive control. (D) Electron microscopy. The tumor cells are characterized by uniform non-enlarged nuclei and a cytoplasm shows numerous pleiomorphic (rounded, polygonal, and rhomboidal) dense deposits, consistent with renin crystals.