glomus tumor


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  • Clinical

    • site: distal extremities, rarely in stomach
    • size: < 1cm

  • Histology

    • Components
      • glomus cells: small, round, central nuclei, surrounded by basal lamina
      • vessels
      • smooth muscle
    • Subcategories
      • solid glomus tumor
        • 75%
        • nests of glomus cells, capillaries
      • glomangioma
        • 20%
        • small clusters of glomus cells, dilated veins
      • glomangiomyoma
        • nests of glomus cells and smooth muscle, staghorn clefts

  • Atypical variants

    • glomangiomatosis
      • resembles diffuse angiomatosis
      • but has glomus cell nodules in vascular walls
    • symplastic glomus tumor
      • degenerative atypia
      • but no real atypia, necrosis or mitosis
    • malignant glomus tumor
      • size > 2cm and subfascial or visceral location
      • atypical mitotic figures
      • marked nuclear atypia
    • glomus tumor of uncertain malignant potential
      • has some but not all of the malignant features

  • Stains

    • positive: SMA, type IV collagen, h-caldesmon
    • negative: desmin, CD34, CK, S100
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