Overview
Leukaemia is an umbrella term for a group of haematological malignancies that originate in the bone marrow, resulting in high numbers of abnormal blood cells.
Leukaemia can be classified according to the following:
- Acute or chronic?
- What cell lineage are the abnormal cells from? Are they myeloid or lymphoid?
Classification
Acute vs. chronic leukaemia
Leukaemia is first classified based on whether it is acute or chronic. This is according to the degree of cell differentiation (i.e. are the cells immature, mature, or mixed?) and not the duration of the disease. In general:
- In acute leukaemias:
- There are rapid increases in the number of immature blood cells
- This leads to the bone marrow being unable to make healthy cells leading to low haemoglobin and platelets
- In chronic leukaemias:
- There is a build-up of more mature but abnormal blood cells
- They usually take months or years to progress
Myeloid or lymphoid leukaemia
They are then classified based on the predominant cell type involved i.e. myeloid or lymphoid. In general:
- In myeloid leukaemias:
- The malignancy is in a type of cell that normally forms cells from the myeloid cell lineage e.g. red blood cells, neutrophils, platelets etc.
- In lymphoblastic or lymphocytic leukaemias:
The malignancy is in a type of cell that normally forms cells from the lymphoid lineage e.g. B-cells (most commonly affected), and T-cells.
General Features
Generally, features of leukaemia include:
- Constitutional symptoms – fever, weight loss, fatigue, night sweats
- Pallor
- Bruising, prolonged bleeding
- Palpitations
- Recurrent infections
General Investigations
Key investigations for haematological malignancies include:
- Full blood count (FBC):
- Shows derangements in cell numbers depending on lineage
- Blood film:
- May show characteristic cell shapes/changes
- Immunophenotyping:
- Flow cytometry is performed to identify specific markers associated with malignant cells
- Bone marrow biopsy:
- Often used to make a definitive diagnosis
