What is the management of renin-secreting tumors?

Management of Renin-Secreting Tumors

Surgical excision with nephron-sparing surgery (partial nephrectomy) is the definitive treatment for renin-secreting tumors, which provides curative outcomes with resolution of hypertension and hypokalemia within one week of surgery. 1

Diagnosis

Renin-secreting tumors (reninomas) are rare juxtaglomerular cell tumors that cause secondary hypertension through excessive renin production. Proper diagnosis requires:

• Clinical presentation:

  • Severe hypertension (often paroxysmal and poorly controlled)
  • Hypokalemia (though not present in all cases)
  • Secondary hyperaldosteronism
  • Elevated plasma renin activity (PRA)

• Imaging studies:

  • CT scan is the most reliable diagnostic tool, detecting renal masses even when other imaging studies are negative 2
  • Renal ultrasound may identify the mass but is less sensitive
  • Renal angiography may show an avascular area corresponding to the tumor, though it can be initially negative in >50% of cases 3, 2

• Laboratory confirmation:

  • Renal vein sampling for renin measurements (though this fails to provide adequate localization in approximately 52% of cases) 2
  • Direct radioimmunoassay showing markedly elevated total plasma renin 3
  • CT-directed needle biopsy can provide definitive diagnosis in challenging cases 4

Treatment Algorithm

1. Preoperative medical management:

   • Calcium channel blockers (e.g., nifedipine) are effective for controlling hypertension until definitive treatment 2
   • Other antihypertensives targeting the renin-angiotensin system may be used (ACE inhibitors, ARBs, beta-blockers)
   • Potassium supplementation for hypokalemia

2. Definitive treatment:

   • Partial nephrectomy is the standard of care and is feasible in most cases 1
   • For small cortical tumors (<4 cm), nephron-sparing approaches should be prioritized 5
   • Perioperative ultrasonography is useful for localizing intraparenchymal tumors during surgery 1

3. Surgical approach options:

   • Open partial nephrectomy
   • Laparoscopic partial nephrectomy
   • Robot-assisted laparoscopic partial nephrectomy
   • The choice depends on tumor size, location, and surgeon expertise 5

Post-Treatment Follow-up

• Blood pressure and serum potassium levels typically normalize within one week after successful tumor removal 1
• Follow-up should include:
  • Periodic medical history, physical examination, laboratory studies (including serum creatinine, eGFR, and urinalysis) 5
  • Monitoring for potential recurrence, though long-term studies show no tumor recurrence at a mean follow-up of 98 months 1

Special Considerations

• Diagnostic pitfalls: Reninomas can be difficult to diagnose, with patients often followed for several years before correct diagnosis and treatment 3
• Age distribution: Teenagers constitute the largest single population with reninomas (39%), with approximately two-thirds of cases occurring in females 2
• Tumor characteristics: Mean tumor size is approximately 24 mm (range 10-50 mm) 1
• Long-term outcomes: Complete resolution of hypertension and hypokalemia can be expected after successful tumor removal, with excellent long-term prognosis 1

The rarity of these tumors necessitates a high index of suspicion in young patients with severe hypertension and hypokalemia. Early diagnosis and appropriate surgical intervention lead to excellent outcomes with minimal morbidity.