BLL


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  • Clinical

    • ALL = leukemia = involves blood, marrow = 80% B lineage
    • LBL = lymphoma = nodal or extranodal mass lesion = 90% T lineage
    • children (75% has age < 6)
    • 25% marrow blast for diagnosis and treatment purposes
    • unfavorable: t(9;22), age < 1 or >= 10, hyperleukocytosis, slow response to therapy
    • favorable: TEL-AML1 t(12;21), hyperdiploidy, t(1;19)

  • Morphology

    • lymphoblasts
      • larger ones with dispersed chromatin, nucleoli and some grey cytoplasm. Can have azurophilic granules.
      • smaller ones with condensed chromatin, indistinct nucleoli and scant cytoplasm
    • vs hematogones
      • smaller
      • even higher NC ratio
      • homogeneous chromatin
      • no nucleoli
      • has scattered TdT, do not form distinct clusters
      • can be found in marrow of young pt, but is not normal in blood
    • lymphoma has diffuse or single file infiltrate pattern
    • can have lots of mitosis, giving a starry sky look

  • Immunophenotype

    • blasts for distinct clusters/aggregates/sheets and has diffuse TdT positivity
    • positive: CD19, TdT, CD10
    • other positives: CD22, CD24, PAX5, CD79a
    • variable: CD20, CD34
    • can have aberrant: CD13, CD33

  • Molecular

    • IGH rearrangement
    • 70% have TCR rearrangement

  • Recurrent genetic abnormalities

    • t(9;22)(q34;q11.2) BCR-ABL1: aberrant CD13, 33, CD25 association, bad prognosis
    • BCR-ABL-like: CRLF2, EPOR, adult > child, bad prognosis
    • t(v;11q23) KMT2A: CD10-, CD24-, CD15+, NG2+, bad prognosis
    • t(12;21)(p13;q22) TEL-AML1 ETV6-RUNX1: often CD34+, good prognosis
    • hyperdiploidy: 50+ chromosomes, good prognosis
    • hypodiploidy: < 44 chromosomes, bad prognosis
    • t(5;14)(q31;q32) IL3-IGH: eosinophilia, diagnostic even if low blast count
    • t(1;19)(q23;p13.3) E2A-PBX1 TCF3-PBX1: CD9+
    • iAMP21: 5+ RUNX1 by FISH or 3+ on one chromosome, bad prognosis
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