Based upon the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (2008), classification incorporates morphologic, immunophenotypic, genetic and clinical features in an attempt to define entities that are biologically homogeneous and that have clinical relevance.
The acute leukaemias are classified as myeloid or lymphoid based on the lineage of the blast cells.Tests performed on the Bone marrow biopsy used for classification and risk stratification include:
1. Flow cytometry
3. Cytogenetics - oncology
4. Molecular genetics – FLT3, NPM1, CEPBalpha.
The testing of other oncogenes is becoming more common in some institutions, though their utility in risk stratification is yet to be fully defined.
Acute leukaemias are classified into three main groups:
1. Acute myeloid leukaemia (AML) and related precursors neoplasms, which in turn comprise
a. AML with recurrent genetic abnormalities, including AML with gene mutations (FLT3-ITD, NPM1, CEPBA)
b. AML with myelodysplasia-related changes
c. Therapy-related myeloid neoplasms
d. AML, not otherwise specified
e. Myeloid sarcoma
f. Myeloid proliferations related to Down syndrome
g. Blastic plasmacytoid dendritic cell neoplasm
2. Precursor lymphoid neoplasms, which in turn cocmprise:
a. B lymphoblastic leukaemia/lymphoma
b. T lymphoblastic leukaemia/lymphoma
3. Acute leukaemias of ambiguous lineage
Information of further subclassification can be found in the reference belowa