Sandbox:Sara

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]

Microscopic features include:

• Non-circumscribed
• Highly cellular with cells having following characteristics:
  • Monomorphic
  • Thin
  • Spindly
  • Scant eosinophilic cytoplasm
  • Hyperchromatic nuclei (resembling neurofibroma)
• Tight storiform pattern (cells radiating in spokes at right angles around a central point that often contains a vessel) infiltrating deeply into subcutaneous tissue and entraping fat cells to form a characteristic honeycomb pattern
• Areas of fascicular growth (seen in some cases)
• The early plaque stage may lack the particular storiform pattern
• Many non-atypical mitotic figures may be present
• Non-polarized, thin collagen
• Mild pleomorphism (not significant)
• Focal atypia
• May coexist with giant cell fibroblastoma
• Absent or rare histiocytes
• Following cell types are absent:
  • Histiocyte-like cells
  • Foam cells
  • Giant cells
  • Other inflammatory cells
• Different variants include:
  • Atrophic (depressed lesion)
  • Collagenous (with central thick collagen bundles)
  • Granular cell (S100 negative)
  • Myxoid
  • Palisading
  • Pigmented
  • Sclerosing