+ 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