Acute Lymphoblastic Leukaemia

Pathology:

Acute lymphoblastic leukaemia (ALL) is a malignant proliferation of haematopoietic precursor blast cells of lymphoid lineage.

Aetiology:

The aetiology of ALL is currently unknown, although certain predisposing factors, such as ionising radiation and congenital chromosomal abnormalities, may play a role.

Frequency:

ALL is the most commonly observed leukaemia in children, with a median age of diagnosis of 3.5 years, although it is rare in adults.

Philadelphia Chromosome:

The Philadelphia Chromosome is a chromosomal abnormality, seen in approximately 25% of cases, which results from the translocation of genetic material between chromosomes 9 and 22. This forms a hybrid gene combining BCR and ABL, and leads to increased tyrosine kinase activity.

Symptoms:

The most common symptoms associated with ALL are anaemia, infection, haemorrhage, failure to thrive, and bone or joint pain.

Signs:

• Enlargement of the spleen and liver (hepato-splenomegaly).
• Lymphadenopathy.

Investigations:

• Bloods: A full blood count (FBC) can show normochromic normocytic anaemia, as well as increased white blood cells and decreased platelets and reticulocytes.
• Blood Film: A blood film would identify the presence of the lymphoblasts.
• Bone Marrow Aspirate: An aspirate can also be used to identify the lymphoblasts, which can make up 20% or more of the aspirate.
• Imaging: A chest X-Ray can also be used to assess for any mediastinal mass, which can be present in cases of T-lineage ALL.
• Cytogenetics: Cytogenetic analysis can be used to identify the presence of the Philadelphia Chromosome.

Treatment:

Medical: Treatment of ALL can involve the use of antibiotics and other medications to treat and prevent infections; transfusions to replace lost blood; chemotherapy to kill cancerous cells; immunotherapy to boost the body's natural defences; and stem cell transplantation.

Complications:

• Infection.
• Bleeding.
• Organ damage.
• Hair loss.
• Gastrointestinal (GI) toxicity.
• Infertility.

Prognosis:

The outlook is positive for children with ALL, with over 80% cure rates. Unfortunately, the prognosis for adults is poorer, as relapse rates tend to be higher.