Reninoma Presenting in Pregnancy

A 23-year-old Caucasian female was diagnosed with hypertension and controlled with an angiotensin-converting enzyme inhibitor and a beta-blocker. Two years later, she developed hypokalemia. She had normal urine and plasma catecholamines and metanephrines, and aldosterone was appropriately suppressed in a saline suppression test. Computed tomography angiogram (CTA) and magnetic resonance angiography did not detect structural renal or adrenal causes. She then became pregnant; the angiotensin-converting enzyme inhibitor was changed to a calcium channel blocker and methyldopa, without however maintaining adequate control. At 26 weeks of pregnancy, she underwent cesarean section for hemolysis, elevated liver enzymes, and low platelet count (HELLP syndrome); the newborn infant died after a 4-week complicated course in intensive care. The patient was referred later to the National Institutes of Health for uncontrolled hypertension. Her upright plasma renin activity was 20 ng/mL/h (normal, <4.3), and her aldosterone level was 110 ng/dL (normal, <21). CTA, magnetic resonance angiography, positron emission tomography, and renal venous sampling established the diagnosis of a 1-cm left kidney renin-secreting lesion (Figure 1, A–C and E). Her blood pressure normalized immediately after a left partial nephrectomy. Histopathology was consistent with a juxtaglomerular cell tumor (Figure 1, D, F, and G). Today, more than 1 year later, she remains off all medications.

Figure 1.

The reninoma (indicated by arrows) was localized by CTA (A), maximum intensity projection (B), and positron emission tomography/computed tomography (C). D, Actual tumor size was 1.4 × 1.2 × 0.8 cm. E, Results of renal venous sampling performed as previously described (1, 2); the patient received furosemide 20 mg/d before and 1.25 mg enalaprilat during the procedure. The highest stimulated plasma renin activity corresponded to the drainage of the lesion identified in the scans. Immunohistochemistry confirmed a CD34-positive reninoma (F, hematoxylin and eosin staining; G, CD34 staining).

Given the tumor's preponderance in young females (1, 2), this is surprisingly only the fifth report describing pregnancy outcome in a patient with reninoma (2–6). Three of four previous reports showed poor outcomes including preterm labor and an intrauterine fetal demise. In four of five cases, the tumor was diagnosed years after the delivery.

We conclude that clinicians should consider this rare etiology in young women with uncontrollable hypertension. If adequate pharmacological control is not achieved during pregnancy, surgical ablation of the tumor should be considered, given the risks of fetal or neonatal demise. Earlier diagnosis of a reninoma may lead to better outcomes associated with this otherwise benign tumor.