Acute myeloid leukaemia (AML) with mutated NPM1 carries mutations that usually involve exon 12 of NPM1. Here are some key points to remember.
1. There is a female predominance in this type of AML.
2. There is a strong association between both acute myelomonocytic and acute monocytic leukaemia and NPM1 mutation.
3. Charactistic cup-shaped blasts are seen.
4. Immunophenotype: AML with mutated NPM1 is character ized by high CD33 expression and variable (often low) CD13 expression.
5. Immunophenotype: KIT (CD117), CD123, and CD110 expres sion are common.
6. Immunophenotype: HLA―DR and CD 34 is often negative.
7. Two major subgroups of AML with mutated NPM1 have been described: one with an immature myeloid immunophenotypic profile and one with a monocytic (CD36+, CD64+, CD14+) immunophenotypic profile.
8. Immunohistochemical detection of cytoplasmic NPM1 is predictive of NPM1 mutations. Remember that normally NPM-1 is expressed as nucleolar positivity.
9. Cases with a normal karyotype, in the absence of FLT3―ITD mutation, have a characteristically favourable prognosis.
10. Co-occurrence of NPM1, FLT3-ITD, and DNMT3A muta tions has been associated with a particularly poor outcome.
Hope you remember these key points for your boards!
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