Acute Lymphocytic Leukemia  Acute Lymphocytic Leukemia  Clinical
Features Laboratory Features and Diagnostic Workup Biologic and
Prognostic Investigations   Acute lymphocytic leukemia (ALL) is
a malignant disorder resulting from the clonal proliferation of
lymphoid precursors with arrested maturation [1]. The disease
can originate in lymphoid cells of different lineages, thus
giving rise to B- or T-cell leukemias or sometimes mixed-lineage
leukemia.  The disease has historic relevance because it was one
of the first malignancies reported to respond to chemotherapy
[2] and was later among the first malignancies cured in a
majority of children [3]. Since then, much progress has been
made, not only in terms of treatment, but, importantly, in
deciphering the heterogeneity of ALLs.  As information
accumulates about molecular aberrations, immunophenotyping,
chromosomal abnormalities, and prognostic factors, more rational
therapies have been designed. Because most cases are diagnosed
in children [4], our current kno