solitary fibrous tumor


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  • Overlapping entities

    • hemangiopericytoma
      • more hypercellular
    • lipomatous hemangiopericytoma
      • has mature fat
    • giant cell angiofibroma
      • multinucleated giant cells

  • Clinical

    • age: middle-aged
    • site: anywhere
    • size: 1-25 cm, median 5-8 cm
    • can be benign or malignant

  • Histology

    • patternless architecture
    • hypercellular and hypocellular areas
    • spindle cells
    • hyaline, keloid-like collagen
    • staghorn/branching vessels
    • malignant features
      • hypercellular
      • atypia
      • tumor necrosis
      • mitosis >= 4 per 10hpf
      • infiltrative margin

  • Stains

    • CD34+ (90-95%), CD99+ (70%)
    • 20-35% stain EMA, BCL2, SMA
    • lipomatous hemangiopericytoma has more CD99 and BCL2

  • Molecular

    • NAB2-STAT6 gene fusion
    		•