+ General Considerations

  • Sites: skin, subcutis, and oral cavity
  • Low-grade histology: increased collagen content and low mitotic figures
  • High-grade histology: very cellular with closely packed spindle-shaped fibroblasts with many mitotic figures
  • Histologically low-grade, biologically high-grade FSA is a variant in the oral cavity that tends to grow to a large size and invade into deeper structures including bone
  • Distant metastasis in up to 20%
  • Low-grade FSA can be difficult to differentiate histologically from fibroma, nodular fasciitis, aggressive fibromatosis, and chronic inflammatory reactions

+ Feline Fibrosarcoma

  • 12%-15% of feline skin tumors
  • Multiple FSA in cats with feline sarcoma virus (FeSV) infection
  • FeSV will not cause neoplasia alone, not transmitted horizontally and requires FeLV for replication
  • FeSV is not associated with solitary FSA of older cats

See Vaccine-Associated and Soft Tissue Sarcomas for more information