Acute myeloid leukaemia
Acute myeloid leukaemia (AML)
accounts for 75% of all childhood malig-nancies and <20% of all acute
leukaemias. It is also known as acute non-lymphoblastic leukaemia (ANLL). AML
results from malignant prolifera-tion of myeloid cell precursors. AML can be
subdivided morphologically using the French–American–British (FAB)
classification system:
· M1:
AML without maturation.
· M2:
AML with maturation.
· M3:
acute promyelocytic leukaemia
(PML).
· M4:
acute myelomonocytic leukaemia
with eosinophilia (M4Eo).
· M5:
acute monocytic/monoblastic
leukaemia.
· M6:
acute erythroleukaemia.
· M7:
acute megakaryocytic leukaemia.
· Symptoms and signs of bone marrow
replacement.
· Lymphadenopathy less prominent
than in ALL.
· Intrathoracic extramedullary
disease less common than in ALL.
· M3 may present with coagulopathy
from proteolytic enzyme activity.
· Solid deposits (chloroma)
occasionally seen in M2, M4, or M5.
Cytogenetic analysis shows characteristic
abnormalities:
· M1
and M2 AML: t(8;21)
translocation observed in 15% of all cases.
· M3
AML: t(15;17)
translocation observed in 100% of cases;
· M4Eo:
inv(16) frequently observed.
These translocations are regarded
as good prognostic indicators. Other complex karyotypes are associated with
poor risk.
In AML prolonged continuation
therapy is not used:
· 4 courses intensive myeloablative
chemotherapy. The role of the gemtuzumab or Myelotarg (a monoclonal antibody
directed against CD33) given alongside chemotherapy is being explored in the
context of clinical trials.
· PML:
all-trans retinoic acid given in
induction, before chemotherapy, improves
survival.
· High risk cases, including those
who fail to achieve complete remission
after 2 courses, are usually
offered BMT in first remission.
Overall survival is >60%.
All cases require BMT after
intensive re-induction, usually in conjunction with ‘FLAG’ or ‘FLAG-Ida’
regimen (i.e. fludarabine, ara-C, and G-CSF sup-port +- idarubicin).
The risk of developing acute
leukaemia is increased 20–30 times, com-monly either a pre-B (common) ALL or
AML (especially M7). Response to chemotherapy is good and better relapse-free
survival is found in those with AML. Children with Down syndrome-associated
leukemia experi-ence more complications of treatment.
·Fanconi syndrome.
·Bloom syndrome.
·Ataxia telangiectasia.
·Kostmann’s syndrome.
·Diamond–Blackfan syndrome.
·Klinefelter’s.
·Turner’s syndrome.
·Neurofibromatosis.
·Incontinentia pigmenti.
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