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Leukemia - Acute

PreB ALL

B lymphoblastic leukemia / lymphoma with t(12;21)(p13;q22); TEL-AML1 (ETV6-RUNX1)


Reviewer: Daniela Mihova, M.D. (see Reviewers page)
Revised: 2 February 17 January 2013, last major update September 2012
Copyright: (c) 2001-2013, PathologyOutlines.com, Inc.

General
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● 20-30% of childhood preB ALL; most common translocation (Chin Med J (Engl) 2003;116:1298, Atlas of Genetics and Cytogenetics in Oncology and Haematology), but not infants; also 3% of adults
● 5 different patterns of gene expression involving 14 genes, can detect with gene chip (BMC Genomics 2007;8:385)
● Excellent prognosis due to good response to chemotherapy; 90% remissions; relapses occur later than other ALL
● Persistence of TEL-AML1 transcripts is not necessarily related to relapse (Pediatr Int 2003;45:275)

Micro description
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● No distinct morphology

Positive stains
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● CD10 (bright), CD19, CD34, HLA-DR
● Also CD13 and CD33 (Diagn Mol Pathol 2000;9:184)

Negative stains
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● CD9, CD20

Molecular description
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● Fusion of TEL/ETV6 and AML1/RUNX1/CBFA2 genes
● Detect with FISH or PCR; not found by conventional cytogenetics (i.e. are cryptic) because rearranged segments are too small;
● May have no other molecular abnormalities, almost never > 50 chromosomes

Molecular images
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FISH: t(12;21)(p13;q22)

End of Leukemia - Acute > PreB ALL > B lymphoblastic leukemia / lymphoma with t(12;21)(p13;q22); TEL-AML1 (ETV6-RUNX1)


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