Bosniak Classification for Complex Renal Cysts Reevaluated: A Systematic Review

Area of Science:

• Urology
• Radiology
• Oncology

Background:

• The Bosniak classification system is widely used for evaluating complex renal cysts.
• Accurate cyst characterization is crucial for guiding treatment decisions and predicting oncologic outcomes.

Purpose of the Study:

• To systematically evaluate the Bosniak classification system's accuracy in predicting malignancy rates for each category.
• To assess the effectiveness of surgical treatment and oncologic outcomes (recurrence/metastasis) based on Bosniak categories.

Main Methods:

• A systematic review and meta-analysis of 39 publications adhering to PRISMA and QUADAS-2 criteria.
• Cysts were categorized into Bosniak II, IIF, III, and IV, analyzed in surgical and radiological cohorts.

Main Results:

• Malignancy rates were 51% for Bosniak III and 89% for Bosniak IV cysts.
• Stable Bosniak IIF cysts had <1% malignancy; reclassified IIF cysts showed 85% malignancy.
• Number needed to treat to avoid metastasis was 140 for Bosniak III and 40 for Bosniak IV cysts.

Conclusions:

• The Bosniak classification is highly effective for categories II, IIF, and IV, but less so for category III, with 49% of category III cysts being overtreated.
• Surveillance may be a rational alternative to surgery for Bosniak III cysts, though further studies are needed to confirm its safety.