When to manage renal cysts?

From the Guidelines

Renal cysts should be managed when they are symptomatic, complex, or suspicious for malignancy, with a focus on active surveillance for small, asymptomatic cysts and intervention for those with concerning features or significant growth. The management of renal cysts depends on various factors, including the size, complexity, and symptoms associated with the cyst. Simple renal cysts, which are common and found in up to 50% of people over age 50, typically require no treatment if they are asymptomatic, small, and have typical benign features on imaging (thin-walled, fluid-filled, no solid components) 1. Some key points to consider in the management of renal cysts include:

• Intervention is warranted when cysts cause pain, hematuria, hypertension, or obstruction of the collecting system.
• Complex cysts with concerning features like irregular walls, calcifications, solid components, or enhancement on contrast imaging (Bosniak category III or IV) should be evaluated for potential malignancy, often requiring surgical removal 1.
• Active surveillance with periodic imaging is recommended for indeterminate cysts (Bosniak IIF) to detect changes that might indicate malignant transformation 1.
• The Bosniak classification is a useful tool in predicting the risk of malignancy and guiding management, with Bosniak I, II, IIF, III, and IV cysts having approximately 0%, 0%, 10%, 50%, and 100% risk of malignancy, respectively 1.
• For patients with a solid or Bosniak 3/4 complex cystic renal mass, clinicians should consider renal mass biopsy for further oncologic risk stratification and assign CKD stage based on glomerular filtration rate (GFR) and degree of proteinuria 1. In general, the management of renal cysts should prioritize a patient-centered approach, taking into account the individual's overall health, life expectancy, and preferences, with a focus on minimizing morbidity, mortality, and improving quality of life.

From the Research

Renal Cyst Management

• Renal cysts are common, with a prevalence of about 5% in the population 2
• The management of renal cysts depends on their characteristics, such as size, location, and symptoms
• Simple renal cysts (Bosniak type I & II) are usually asymptomatic and do not require treatment, while complex cysts (Bosniak type III & IV) may require further evaluation and management 2, 3

Indications for Management

• Symptomatic renal cysts, such as those causing pain, hemorrhage, infection, hydronephrosis, or hypertension, require management 2, 4
• Complex renal cysts, such as those with a high risk of malignancy, require further evaluation and management 3
• Large or recurrent symptomatic cysts may require surgical decortication or laparoscopic surgery 2, 4

Management Options

• Percutaneous aspiration alone or with sclerotherapy is often the first-line treatment for simple symptomatic cysts 2, 4
• Laparoscopic surgery, including transperitoneal or retroperitoneal approaches, is highly efficacious and associated with high satisfaction rates and minimal morbidity 2, 5
• Robot-assisted surgical management may be used for complex cysts, but its benefits are not outstanding, and it is associated with added cost 2

Diagnostic Evaluation

• Ultrasound-guided percutaneous cyst puncture with cytological analysis of the cyst content, or computerized tomography, are useful in characterizing the cyst and determining the need for management 6
• Bosniak classification is a valuable tool for clinicians to characterize renal cysts and determine the risk of malignancy 2, 3
• Percutaneous biopsy of complex renal cysts is well tolerated and accurate for diagnosis, but its use is dependent on interobserver variability and clinical judgment 3