title: Acute lymphoblastic leukaemia: diagnosis and classification.
abstract: Acute lymphoblastic leukaemia (ALL) is a heterogeneous disease with distinct biological and prognostic groupings. Diagnosis relies on traditional cytomorphological and immunohistochemical evaluation of the leukaemic blasts. Subsequently, cytogenetic analysis identifies clonal numeric and/or structural chromosomal abnormalities that may be present, thus confirming the subtype classification and providing important prognostic information for treatment planning. The major chromosomal abnormalities in ALL are t(9;22)(q34;q11), t(12;21)(p13;q22), t(4;11)(q21;q23), t(1;19)(q23;p13), 8q24 translocations and hyperdiploidy. Generally, hyperdiploidy, occurring most frequently in paediatric cases, is associated with a good prognosis, while hypodiploidy confers a poor prognosis. Among structural chromosomal abnormalities, the t(9;22)(q34;q11) resulting in the BCR/ABL fusion protein, and rearrangements of the MLL gene, confer a poor prognosis in both children and adults, while t(12;21)(p13;q22), resulting in the TEL/AML1 fusion protein, and del (12p) confer a good prognosis. More recently, additional diagnostic and prognostic information has been gained from fluorescence in situ hybridization (FISH) and DNA microarray techniques.
authors.affiliation: Section of Hematology/Oncology, Department of Medicine and Cancer Research Center, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Partow
authors.initials: P
authors.lastname: Kebriaei
authors.forename: John
authors.initials: J
authors.lastname: Anastasi
authors.forename: Richard A
authors.initials: RA
authors.lastname: Larson
mesh_terms: D019070:Cell Lineage / Q000235:genetics; D002869:Chromosome Aberrations; D003584:Cytological Techniques / Q000379:methods; D016147:Genes, Tumor Suppressor; D006801:Humans; D016130:Immunophenotyping; D020411:Oligonucleotide Array Sequence Analysis; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D011379:Prognosis