What is the treatment for renal cortical cyst?

Management of Renal Cortical Cysts

For simple renal cortical cysts (Bosniak I and II), no prescription or intervention is required—these benign lesions need no treatment or routine follow-up imaging. 1, 2

Classification-Based Management Algorithm

Simple Cysts (Bosniak I and II)

• Asymptomatic simple cysts require no intervention regardless of size, as they carry approximately 0% malignancy risk 1, 2
• These cysts are characterized by well-defined margins, absence of internal echoes on ultrasound, and no contrast enhancement on CT or MRI 1, 2
• No routine follow-up imaging is necessary for confirmed simple cysts 1

Symptomatic Simple Cysts

When simple cysts cause pain, hypertension, infection, or urinary obstruction, treatment options include:

First-line intervention:

• Percutaneous aspiration with ethanol sclerotherapy is the preferred initial treatment, achieving efficacy rates up to 97% 3
• Simple aspiration alone has high recurrence rates (20-80%) and should be avoided 3
• Ethanol is the most commonly used and effective sclerosing agent 3

Second-line intervention:

• Laparoscopic cyst decortication is the gold standard for large symptomatic cysts, especially in younger patients 3, 4
• Retroperitoneal approach is preferred for infected cysts to avoid peritoneal contamination 4
• This approach offers high efficacy with minimal morbidity and high patient satisfaction 4

Moderately Complex Cysts (Bosniak IIF)

• Active surveillance with repeat CT or MRI imaging in 6-12 months is recommended, as these carry approximately 10% malignancy risk 1, 2
• Contrast-enhanced imaging is preferred for follow-up 1

Complex Cysts (Bosniak III and IV)

• Intervention is recommended when oncologic benefits outweigh risks, as Bosniak III cysts have ~50% malignancy risk and Bosniak IV cysts have ~100% malignancy risk 1, 2
• Partial nephrectomy should be prioritized for cT1a renal masses (<7 cm) when intervention is indicated 1, 2
• Consider renal mass biopsy for further risk stratification, though core biopsies have limited utility for cystic masses unless solid components are present 1, 2
• Repeat cross-sectional imaging in 3-6 months to assess for interval growth may be appropriate 1
• Active surveillance is an option for small (<2 cm) complex cystic masses in well-selected patients, with cancer-specific survival rates exceeding 95% 2

Special Clinical Scenarios

Hypertension Associated with Renal Cysts

• Large cortical cysts can cause hypertension through renal parenchymal compression or vascular stretching 5
• Cyst marsupialization or decortication may improve blood pressure control in selected cases 5

Infected or Complicated Cysts

• Percutaneous drainage is appropriate for infected cysts, with fluid sent for culture 6
• Antibiotics should be guided by culture results 6

Pediatric Considerations

• A solitary cyst in childhood requires follow-up imaging, as it may indicate autosomal dominant polycystic kidney disease in children with positive family history 2

Critical Pitfalls to Avoid

• Never perform surgery on Bosniak II cysts—this constitutes overtreatment 1
• Never assume a nondiagnostic biopsy indicates benignity—consider repeat biopsy or surgical resection 2
• Small cysts (<1.5 cm) can be challenging to evaluate with CT due to pseudoenhancement and partial volume averaging 1
• Approximately 30% of recurrences after treatment of malignant lesions are discovered after 5 years, necessitating long-term surveillance for treated complex cysts 1