ISUP Consensus Definition of Cribriform Pattern Prostate Cancer

Area of Science:

• Uropathology
• Oncology
• Diagnostic Pathology

Background:

• Cribriform pattern in prostate cancer is a significant adverse prognostic indicator.
• The International Society of Urological Pathology (ISUP) recommends its inclusion in standard reporting.
• Improving interobserver agreement for cribriform pattern diagnosis is crucial.

Purpose of the Study:

• To establish a consensus definition for cribriform pattern in prostate cancer.
• To enhance the reproducibility of cribriform pattern diagnosis among pathologists.
• To provide practical diagnostic criteria for clinical reporting.

Main Methods:

• Convened an international panel of 12 expert urogenital pathologists.
• Utilized the Delphi method for consensus building over two rounds.
• Reviewed a curated set of 32 images representing challenging diagnostic categories.
• Conducted a virtual meeting to discuss images and refine diagnostic criteria.

Main Results:

• A consensus definition of cribriform pattern was approved: "A confluent sheet of contiguous malignant epithelial cells with multiple glandular lumina that are easily visible at low power (objective magnification ×10). There should be no intervening stroma or mucin separating individual or fused glandular structures."
• Explanatory notes were developed to support the definition.
• The definition and criteria aim for practical application in pathology reporting.

Conclusions:

• The developed consensus definition is practical and facilitates reproducible recognition of cribriform pattern.
• Standardized reporting of this clinically important pattern will improve patient management.
• Educational resources, including an image slide set, are available from ISUP.