Are there exceptions to the 20% blast threshold for AML?

Yes. AML is diagnosed regardless of blast count when certain cytogenetic or molecular abnormalities are present: t(8;21), inv(16)/t(16;16), t(15;17), or biallelic CEBPA mutation. WHO 2022 classification further adds NPM1-mutated AML to this exception list.

How does WHO 2022 classification change AML blast threshold?

WHO 2022 defines AML with myelodysplasia-related changes at any blast count above 10% when MDS-related mutations are present (SRSF2, SF3B1, ASXL1, etc.), removing the strict 20% requirement for this specific subtype.

Blast Count to AML Diagnosis Threshold

Determine whether bone marrow blast percentage meets WHO AML threshold: 20% or more blasts required for AML diagnosis (with exceptions for AML-defining cytogenetics at any blast count).

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Frequently Asked Questions

Are there exceptions to the 20% blast threshold for AML?

How does WHO 2022 classification change AML blast threshold?