fibrosarcoma



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  • Types

    • infantile
      • 1st year of life
      • t(12;15) ETV6 (12p13) NTRK3 (15q25)
      • good prognosis (5% mortality, up to 50% recurrence, rare metastasis)
      • distal extremities > trunk, head/neck
    • adult
      • median age 50
      • extremities, trunk, head/neck
      • no specific genetics
      • poor prognosis
    • bone
      • lytic, moth-eaten bone lesion
      • femur (distal > proximal), distal humerus, proximal tibia
      • poor prognosis

  • Histology

    • spindle cells
    • fascicles, herring-bone pattern
    • keloid-lilke collagen

  • Stains

    • negative SMA, CD34, CK
    • can be occasionally SMA positive due to myofibroblastic differentiation
    • CD34 if arising from DFSP or SFT

  • Ddx

    • DFSP (superficial)
    • liposarcoma (retroperitoneal)
    • leiomyosarcoma (strong SMA)
    • synovial sarcoma
    • undifferentiated pleomorphic sarcoma (marked atypia, storiform)
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