Chapter 17 in
haematology (Acute lymphoblastic leukaemia)summary
-Acute lymphoblastic leukaemia
(ALL) is casued by an accumulation of lymphoblasts in
the bone marrow. It isthe most common malignant disease of clidhood-75% of
cases occur before the age of 6 years. Eighlty-five per cent of cases are of
B-cell lineage with the rest being of T-cell lineage.
-The first genetic mutation ocuurs in amy cases in utero, with a secondary genetic event
occuring later inclidhood,possibly as a reaction to an infection.
-The clinical presentation is with
the features of bone marrow failure (anaemia,infection and bleeding) together
with symptoms of tissue infiltration by tumour cells, leading to bone pain or
swollen lymph nodes.
-Diagnosis is by examination of blood and bone marrow.important tests include microscopic
examination of the tumour cells, immunophenotyping and genetic analysis.
-ALL is subclassified
according to the underlying genetic defect and a wide
varity of genetic lesions are seen . The number of chromosomes in the tuomour
cell has prognostic impotance: hyperdiploid cell have >50 chromosomes and
generally have a good prognosis whereas hypodiploid cases (>44
chromosomes)carry a poor prognosis.
-Treatment protocols for ALL
are extremely complex and usually have four compoents- remission induction
,intensification ,CNS- directed therapy and maintenance.
-Treatment is risk adjusted to reduce the treatment given to patients with good prognosis.This is
based on age ,gender, white cell count and cytogenetics at presenatation.
-Small numbers of tumour
cells may sometimes be detected by FACS or molecular
analysis even when the blod and bone marrow apear to be clear of leukaemia.
This minimal residual disease has prognostic significance and is used in
planing therapy.
-If relapse occurs during
chemotherapy the outlook is poor but if it happens
after years off all treatment the outlook is better. Further chemotheraoy and
allogeneic SCT should be cosidered.
-Overall,85% of chlidren can now expect to be cured. The cure rate in adults drops significantly
to less than 5% over the age of 70 years.
From
book: Essentail Haematology A.V.HOFFBRAND,P.A.H.MOSS.6EDITION
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