Biomedical Engineering Reference
In-Depth Information
2. Leukemia can be classii ed in terms of lineage and degree of maturation of
the predominant malignant cells. h us, there are lymphoid and myeloid
leukemias and each subtype is divided into multiple subtypes based on
morphology and immunological or genetic cell markers. Acute leukemia
is characterized by the appearance of immature, abnormal cells in the bone
marrow and peripheral blood.
3. Acute leukemias are associated with several genetic abnormalities,
which may result from chromosomal abnormalities and/or from gene
mutations.
4. h e genetic abnormalities lead to the deregulation of several molecular
pathways and are associated with the response to treatment and
prognosis.
Key Facts about Acute Promyelocytic Leukemia
1. Acute promyelocytic leukemia is a subtype of acute myelogenous leukemia
characterized by the presence of translocations involving chromosome 17
at the locus of the
Retinoic Acid Receptor
α (RARα). In most patients, the
chromosomal translocation between chromosomes 15 and 17 [t(15;17)] is
detected, which generates the PML-RARα fusion gene.
2. h e leukemic cells of acute promyelocytic leukemia resemble normal
promyelocytes, which are one of the steps during myeloid maturation;
for this reason the leukemic cells are said to present a 'block of
dif erentiation.
3. Treatment with ATRA induces the dif erentiation of the leukemic cells into
mature myeloid cells, thus leading to the remission of acute promyelocytic
leukemia.
4. Although patients with acute promyelocytic leukemia respond well to
treatment with ATRA, they may develop a life-threatening complication
called dif erentiation syndrome, which is characterized by the ini ltration
of lung and other organs by dif erentiating myeloid cells.
5. Changes in the expression of adhesion molecules induced by ATRA play
an important role in the pathophysiology of dif erentiation syndrome.
Definition of Terms
Acute myelogenous leukemia:
A malignant disease of the bone marrow in which
hematopoietic precursors are arrested in an early stage of development. It is characterized
by the presence of more than 20% leukemic cells of myeloid origin in the bone marrow
or blood.
Acute lymphoblastic leukemia:
A malignant (clonal) disease of the bone marrow in which
early lymphoid precursors proliferate and replace the normal hematopoietic cells of the
