Fifth edition WHO classification: mature B-cell neoplasms

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• The World Health Organization (WHO) classification of haematolymphoid tumours is crucial for diagnosing and understanding neoplasms.
• The fifth edition (WHO-HAEM5) introduces significant updates to mature B-cell neoplasms, incorporating advanced technologies like genomics.
• Existing classifications may pose challenges in resource-limited settings due to complex criteria and technology requirements.

Purpose of the Study:

• To review the changes and updates in the classification of mature B-cell neoplasms according to WHO-HAEM5.
• To provide guidance on applying the WHO-HAEM5 classification in resource-limited settings.
• To highlight the hierarchical structure and the distinction between essential and desirable diagnostic criteria.

Main Methods:

• Review of the fifth edition of the WHO classification of haematolymphoid tumours (WHO-HAEM5).
• Analysis of updated definitions and diagnostic criteria for mature B-cell neoplasms.
• Focus on the practical application of the classification in settings with limited resources.

Main Results:

• WHO-HAEM5 expands the entities of mature B-cell neoplasms, with definitions increasingly reliant on genomic data.
• The classification employs a hierarchical structure, allowing for family-level diagnoses when specific entity criteria cannot be met.
• Diagnostic criteria are divided into 'essential' and 'desirable' to aid application in resource-limited settings.

Conclusions:

• The WHO-HAEM5 provides an updated framework for classifying mature B-cell neoplasms, integrating new technologies.
• Its hierarchical approach and tiered criteria enhance its applicability, particularly in resource-limited environments.
• This review offers practical insights for pathologists and hematologists navigating the WHO-HAEM5 classification for B-cell lymphomas.