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Acute lymphoblastic leukemia Treatment Diagnosis Symptoms Prognosis

Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL), also known as acute lymphocytic leukemia, is a cancer of the white blood cells, characterised by the overproduction and continuous multiplication of malignant and immature white blood cells (referred to as lymphoblasts) in the bone marrow. It is a hematological malignancy. It is fatal if left untreated as ALL spreads into the bloodstream and other vital organs quickly (hence "acute"). It mainly affects young children and adults over 50.

ALL accounts for approximately 80 per cent of all childhood leukemia cases, making it the most common type of childhood cancer. It has a peak incident rate of 2-5 years old, decreasing in incidence with increasing age before increasing again at around 50 years old. ALL is slightly more common in males than females.

Classification

Subtyping of the various forms of ALL is done according to the FAB (French-American-British) classification, which is used for all acute leukemias (including acute myelogenous leukemia, AML). As ALL is not a solid tumour, the TxNxMx notation used in those cancers is of little use.

The FAB classification is:

* ALL-L1: small uniform cells
* ALL-L2: large varied cells
* ALL-L3: large varied cells with vacuoles (bubble-like features)

Note: The recent WHO International panel on ALL recommends that this classification be abandoned, since the morphological classification has no clinical or prognostic relevance. It instead, advocates the use of the immunophenotypic classification mentioned below.

Each subtype is then further classified by determining the surface markers of the abnormal lymphocytes, called immunophenotyping. There are three main immunologic types: B-cell, pre-B cell and T-cell. Subtyping helps determine the prognosis and most appropriate treatment in treating ALL.

Some cytogenetic subtypes have a worse prognosis than others. These include:

* A translocation between chromosomes 9 and 22, known as the Philadelphia chromosome, occurs in about 20% of adult and 5% in pediatric cases of ALL.
* A translocation between chromosomes 4 and 11 occurs in about 4% of cases and is most common in infants under 12 months.
* Not all translocations of chromosomes carry a poorer prognosis. Some translocations are relatively favourable.


Acute lymphoblastic leukemia
 
 
 
 
 
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