What is the best management approach for an 83-year-old female with normal renal function, mild bilateral hydronephrosis, a stable 1.3 cm angiomyolipoma (AML) on the right kidney, and a 2 cm simple cyst on the left kidney?

Management of Incidental Renal Findings in an 83-Year-Old Female

For an 83-year-old female with normal renal function and incidental findings of mild bilateral hydronephrosis, a stable 1.3 cm right renal angiomyolipoma, and a 2 cm left renal simple cyst, active surveillance with periodic imaging is the most appropriate management approach.

Assessment of Bilateral Hydronephrosis

Mild bilateral hydronephrosis in an elderly patient requires evaluation to determine the underlying cause:

• Initial evaluation: Review of current imaging to characterize the degree of hydronephrosis and identify potential causes 1
• Potential causes to consider:
  • Bladder outlet obstruction
  • Pelvic organ prolapse
  • Retroperitoneal fibrosis
  • Malignancy
  • Urolithiasis
  • Medication effects

Since the patient has normal renal function, the hydronephrosis is likely not causing significant renal impairment at this time. However, monitoring is essential as progressive dilation of the upper urinary tract can lead to acute kidney injury and permanent nephron loss if not addressed 1.

Management of 1.3 cm Angiomyolipoma (AML)

The 1.3 cm right renal angiomyolipoma that has not significantly changed requires:

• Active surveillance: The American Urological Association (AUA) guidelines support active surveillance for small renal masses, especially those <2 cm 1
• Imaging follow-up: MRI is the preferred modality for monitoring renal lesions, though CT is an acceptable alternative in adults 1, 2
• Follow-up interval: Imaging at 12-month intervals is appropriate for stable, small AMLs 1

The risk of complications from this small, stable AML is minimal. Intervention is typically reserved for:

• AMLs >4 cm (higher bleeding risk)
• Symptomatic lesions
• Rapidly growing lesions (>0.5 cm/year)

Management of 2 cm Simple Renal Cyst

For the 2 cm left renal simple cyst:

• Classification: Likely Bosniak I (simple cyst) based on description 2
• Management: No specific intervention required for asymptomatic simple cysts 2
• Follow-up: No routine follow-up needed unless symptomatic 2

Simple renal cysts are common incidental findings, especially in elderly patients, and rarely require intervention unless they cause symptoms such as pain, hematuria, or obstruction 3.

Comprehensive Management Plan

1. Initial follow-up imaging: MRI of the kidneys (or CT if MRI contraindicated) in 6-12 months to:

   • Assess stability of hydronephrosis
   • Monitor AML size
   • Confirm simple nature of the renal cyst 1, 2

2. Laboratory monitoring:

   • Annual comprehensive metabolic panel to monitor renal function
   • Urinalysis to check for hematuria or infection 1

3. Long-term surveillance:

   • If findings remain stable after initial follow-up, extend imaging interval to every 1-2 years 1
   • Consider alternating between ultrasound and MRI/CT to reduce radiation exposure 2

4. Indications for intervention:

   • Development of symptoms (pain, hematuria)
   • Significant growth of AML (>0.5 cm/year or total size >4 cm)
   • Worsening hydronephrosis with deterioration of renal function 1

Special Considerations

• Age and comorbidities: At 83 years old, the patient's life expectancy and overall health status should be considered when determining surveillance intensity
• Renal function preservation: Maintaining normal renal function should be prioritized in management decisions
• Patient preference: Discussion with the patient about surveillance versus intervention options is important

Conclusion

Given the patient's age, normal renal function, and the small, stable nature of both the angiomyolipoma and simple cyst, active surveillance with periodic imaging is the most appropriate management approach. This strategy balances the low risk of complications from these incidental findings against the potential risks of unnecessary interventions in an elderly patient.