Fifth edition WHO classification: myeloid neoplasms

Area of Science:

• Hematopathology
• Oncology
• Genetics

Background:

• The WHO classification of haematolymphoid tumours (WHO-HEM5) represents a significant update from WHO-HEM4R.
• It emphasizes molecular and genetic insights for diagnosing myeloid neoplasms.

Purpose of the Study:

• To highlight key updates in WHO-HEM5, focusing on genetic criteria for myeloid neoplasm classification.
• To discuss the challenges and strategies for implementing WHO-HEM5 in low- and middle-income countries (LMICs).

Main Methods:

• Review of the fifth edition of the WHO classification of haematolymphoid tumours (WHO-HEM5).
• Analysis of the integration of genetic criteria and updated diagnostic thresholds.
• Exploration of diagnostic strategies for resource-constrained environments.

Main Results:

• WHO-HEM5 defines many myeloid neoplasms by specific genetic abnormalities, enhancing diagnostic precision.
• The 20% blast threshold for acute myeloid leukaemia (AML) with specific genetic alterations has been removed.
• New entities like clonal hematopoiesis and MDS with biallelic TP53 inactivation are recognized.

Conclusions:

• WHO-HEM5 refines the classification and risk stratification of myeloid neoplasms, supporting personalized medicine.
• Integrating molecular diagnostics with traditional methods is crucial for advancing global hematopathology practices.
• Optimizing diagnosis in LMICs requires adapting advanced tools and leveraging fundamental techniques like morphology and immunophenotyping.