From the Guidelines
Kidney cysts should be monitored regularly with imaging and blood tests to prevent complications and protect kidney function, especially in patients with tuberous sclerosis complex (TSC) or polycystic kidney disease (PKD), as recommended by the most recent consensus statement 1.
Key Considerations
- Kidney cysts can be simple or complex, and while most simple cysts are harmless, complex cysts may require evaluation to rule out cancer 1.
- Patients with TSC are at risk of developing kidney cysts, angiomyolipomata, and renal cell carcinoma, and regular monitoring is essential to detect these conditions early 1.
- Treatment options for kidney cysts include draining the cyst with a needle, surgery to remove the cyst, or medications to manage symptoms, and the choice of treatment depends on the size and location of the cyst, as well as the patient's overall health 1.
Monitoring and Prevention
- Regular monitoring of kidney function through blood tests (creatinine, BUN) and imaging (ultrasound or CT scans) is important for anyone with kidney cysts 1.
- Staying well-hydrated, controlling blood pressure (often with ACE inhibitors or ARBs), and limiting salt intake can help protect kidney function 1.
- Patients with PKD may benefit from treatment with tolvaptan (Jinarc/Samsca) to slow disease progression, typically at 45-90 mg twice daily 1.
Treatment Options
- For patients with a solid or complex cystic renal mass, active surveillance or expectant management may be recommended when the anticipated risk of intervention or competing risks of death outweigh the potential oncologic benefits of active treatment 1.
- For patients with a solid or complex cystic renal mass in whom the anticipated oncologic benefits of intervention outweigh the risks of treatment and competing risks of death, active treatment may be recommended 1.
From the Research
Definition and Prevalence of Kidney Cysts
- Kidney cysts are common findings in nearly 10% of the general population 2
- The prevalence of kidney cysts is about 5% in the general population, and they are more common in adults, affecting approximately 50% of individuals older than 50 years 3, 4
Classification of Kidney Cysts
- Kidney cysts are categorized using the Bosniak Classification of Cystic Renal Masses, which determines the likelihood that cysts are malignant or benign 3, 4, 5
- The Bosniak classification categorizes cysts into simple (Bosniak type I & II) or complex (Bosniak type III & IV) cysts with respect to risk of malignancy or other effects on the kidney 3
Management of Kidney Cysts
- Asymptomatic Bosniak class I and II cysts require no further evaluation or follow-up, while symptomatic large simple cysts might require treatment 4
- Bosniak class III and IV cysts might be malignant and require excision 4
- Percutaneous aspiration alone or with sclerotherapy is often the first-line treatment for simple cysts, while surgical decortication is generally reserved for recurrent or very large symptomatic cysts 3
- Laparoscopic surgery is highly efficacious and is associated with high satisfaction rates with minimal morbidity 3
- Ethanol percutaneous sclerotherapy and laparoscopy are the most commonly reported treatment modalities for simple renal cysts 2
Diagnosis and Evaluation of Kidney Cysts
- Computed tomography remains the gold standard for diagnosing kidney cysts, however, newer diagnostic imaging modalities such as contrast-enhanced ultrasonography are demonstrating promising results 5
- Percutaneous biopsy of complex lesions is well tolerated and adequate for diagnosis, and recent literature suggests that it has a good yield and is accurate in the majority of cases 5