Diagnostic Precision or Pitfalls: How to Apply the New Acute Myeloid Leukemia Classification Systems?

Area of Science:

• Hematology
• Oncology
• Genetics

Background:

• The World Health Organization (WHO) classification has historically guided acute myeloid leukemia (AML) diagnosis and treatment.
• In 2022, two new parallel AML classification systems were published: the WHO 5th edition and the International Consortium Classification (ICC).

Purpose of the Study:

• To review and compare the organization, similarities, and differences between the WHO 5th edition and ICC AML classification systems.
• To highlight potential clinical challenges arising from discrepancies between the two systems.

Main Methods:

• Comparative analysis of the WHO 5th edition and ICC AML classification frameworks.
• Identification of key differences in classification criteria, including blast thresholds and modifier assignments.

Main Results:

• The WHO 5th edition and ICC systems demonstrate concordance for most AML cases.
• Significant differences exist in classification framework, AML-defining blast threshold, myelodysplasia-related AML definition, and therapy-related/germline-associated modifier assignment.

Conclusions:

• While largely concordant, the differences between the WHO 5th edition and ICC classifications may impact patient stratification, clinical trial eligibility, and treatment decisions.
• Understanding these distinctions is crucial for consistent application in clinical practice.