SIMPLISTIC CLASSIFICATION OF LYMPHOID LEUKEMIAS

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SIMPLISTIC CLASSIFICATION OF LYMPHOID LEUKEMIAS

• ACUTE LYMPHOID LEUKEMIA
• PRECURSOR B-ALL
• Specific molecular abnormalities
• PRECURSOR T-ALL
• Specific molecular abnormalities
• BURKITTS LEUKEMIA
• CHRONIC LYMPHOID LEUKEMIAS
• B-CLL
• Other

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FOR ALL INTENTS AND PURPOSES B-CLL DOES NOT OCCUR
IN CHILDREN
Of about 5000 childhood leukemias sent to my
reference lab I have seen 2 cases of B-CLL

• Other chronic lymphoproliferative disorders are
  rare in children and are probably best discussed
  under lymphomas

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ACUTE LYMPHOID LEUKEMIAImportant entities

• Precursor B-ALL
• t(922) (BCR-ABL)
• t(v11) MLL
• t(119) (E2A-PBX1)
• t(1221) (TEL-AML1)
• Hyperdiploidy
• ?Hypodiploidy

• Precursor T-ALL
• SCL1(TAL)
• HOX11
• LMO1/2(RBTN1/2)
• LYL1
• ?Primitive T-ALL

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DIFFERENCES BETWEEN ADULT AND CHILDHOOD ALLT-ALL

• No good data on frequency differences among
  genetically-defined groups
• No good data that genetically-defined groups fare
  differently
• Thus, for current purposes, T-ALL in adults and
  children are likely the same disease
• Frequency of T-ALL higher in adults than children

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DIFFERENCES BETWEEN GENETICS IN ADULT AND
CHILDHOOD ALLPRECURSOR B-ALL
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GENETICS AND PROGNOSIS IN CHILDHOOD ALL

• GOOD PROGNOSIS
• Hyperdiploidy
• TEL-AML1
• POOR PROGNOSIS
• BCR-ABL
• MLL
• INTERMEDIATE PROGNOSIS
• E2A-PBX1(if treated appropriately)
• Other

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CHILDHOOD VS ADULT ALLSUMMARY

• Good prognosis genetic lesions in children rare
  in adults and should be considered distinct
  diseases
• There are no significant differences between
  adult or childhood Burkitts leukemia, T-ALL, or
  leukemias with bcr-abl or MLL abnormalities, so
  that any protocols targeting these diseases
  should include both adults and children
• Remaining 40 of childhood precursor B-ALL is not
  noticeably biologically different from adults,
  but still probably fare better