TLL


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  • Clinical

    • ALL = leukemia = involves blood, marrow = 80% B lineage
    • LBL = lymphoma = nodal or extranodal mass lesion = 90% T lineage
    • 25% blasts for diagnosis and treatment purposes
    • frequent mediastinal/thymic involvement
    • pleural effusions common

  • Morphology

    • larger lymphoblasts with dispersed chromatin, nucleoli and some grey cytoplasm
    • smaller lymphoblasts with condensed chromatin, indistinct nucleoli and scant cytoplasm
    • biopsy sections show finely stippled chromatin and indistinct nucleoli
    • nuclei can be convoluted

  • Immunophenotype

    • positive: TdT, cCD3, CD7
    • ETP type (worse prognosis):CD34+, CD1a-
    • variable CD4/8 depending on stage of maturation
    • can have aberrant myeloid: CD13, CD33, CD117

  • Molecular

    • TCR rearrangement
    • 20% have IGH rearrangement
    • TCR cytogenetic abnormalities: 14q11.2, 7q35, 7p14-15
    • most common translocation partners: HOX11, HOX11L2
    • 8p11.2, FGFR1 associated with eosinophilia, myeloid hyperplasia
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