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!