| Introduction
Measuring
WBCs
Myeloid
Leukemias
Lymphoid
Leukemias
Sources
of Error
Quiz
Please |
|
The
special situation of acute promyelocytic leukemia.
Although a variety of chromosomal
abnormalities are recognized in different forms AML, none is as consistent
as the t(15;17) translocation of acute promyelocytic (FAB; M3) leukemia.
-
Pay attention, this is important
for both pathogenesis and treatment.
-
t(15;17) translocation results
in the fusion of a truncated retinoic acid (vitamin A) receptor-alpha
(RAR-alpha) gene.
-
The resulting hybrid mRNA that
can be detected in most M3 cases.
-
The hybrid gene encodes
for an abnormal retinoic acid receptor that blocks myeloid cell
differentiation beyond the promyelocyte.
-
Large doses of all-trans-retinoic
acid will overcome this block, causing the neoplastic promyelocytes
to differentiate into mature neurtophils.
-
Unfortunately, the retinoic
acid treatment does not lead to a cure, and all M3 patients eventually
relapse.
-
Another important feature
of acute promyelocytic leukemia is the release of procoagulants from
the M3 blasts.
-
The procoagulants frequently
produce disseminated intravenous coagulation (DIC) in those with
M3 leukemia.
Exceptions
to the rule.
Back |