How is acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC) defined?

Updated: Jul 28, 2020
  • Author: Angie Duong, MD; Chief Editor: Aliyah R Sohani, MD  more...
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By definition, the diagnosis of acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC) requires the presence of at least 20% blasts in the peripheral blood (PB) and/or bone marrow (BM), an absence of any of the AML-associated recurrent genetic abnormalities seen in AML (such as inv(3), t(6;9), or NPM1 mutation), and the absence of a history of cytotoxic chemotherapy or radiation therapy for an unrelated disease. [7]

In new cases of AML, careful review of the patient's history to identify a previous diagnosis of myelodysplastic syndrome (MDS) or myelodysplastic/myeloproliferative neoplasm (MDS/MPN) and to exclude prior exposure to cytotoxic treatments (chemotherapy and/or radiotherapy) is necessary for proper classification.

The list of AML-MRC-related cytogenetic abnormalities is shown in the section under "Molecular/Genetic Features and Methods."

Lastly, to classify a new diagnosis of AML as having myelodysplasia-related changes based on morphology, dysplasia must be present in at least 50% of the cells in at least two bone marrow cell lines. Additionally, cases of AML with an NPM1 or biallelic CEBPA mutation are classified separately, even if sufficient morphologic evidence of dysplasia is present. [8, 9]


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