ambiguous lineage


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  • Assigning lineage

    • myeloid: MPO or monocytic
      • monocytic: 2 of NSE, CD11c, CD14, CD64, lysozyme
    • T: CD3
      • cytoplasmic+, surface+/-, target epsilon chain for flow
    • B: CD19, CD79a, CD22, CD10
      • CD19 plus 2 of the following: strong CD19, CD79a, cCD22, CD10
    • r/o entities that trump ambiguous lineage
      • AML w aberrant markers: t(8;21), inv16, t(15;17)
      • FGFR1
      • blast phase CML
      • AML with MDS changes
      • therapy related AML

  • Acute undifferentiated leukemia

    • no lineage
    • often express CD34, HLADR, CD38
    • can be TdT+

  • multiple phenotype acute leukemia

    • biphenotypic: one blast population, 2 lineages
      • B/T ALL + MPO
      • B/T ALL + monoblastic
    • bilineal: two blast population, 2 lineages
      • sum of blasts >= 20%
    • MPAL with cytogenetic abnormalities
      • t(9;22) BCR-ABL
      • 11q23 KMT2A
    • treatment: same as ALL
      • age < 40: peds ALL regimen
      • age 40+: adult ALL regimen

  • NK cell lymphoblastic leukemia

    • CD56
    • immature T markers: CD7, CD2, cCD3
    • lacks B and myeloid
    • rule out blastic plasmacytoid dendritic cell leukemia
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