Injection-site sarcoma

Question 1

What kind of product is most commonly and closely associated with sarcoma formation

Answer 1

Vaccines, especially adjuvanted vaccines

Question 2

What is the clinical presentation of FISS

Answer 2

The clinical presentation of FISS is that of a subcutaneous or intramuscular mass occuring at the site of a previous injection (although an injection history may not be known)
- masses are typically nonpainful and firm to fluctuant
- occasionally, large masses are ulcerated
- typically no systemic signs of illness

Question 3

Explain when an owner should seek veterinary assistance in case of FISS

Answer 3

The “3-2-1” recommendation:
- a mass persists at the injection site for more than 3 months after injection
- a mass is present and is larger than 2 cm, regardless of time since injection
- a mass is still increasing in size 1 month after injection

Question 4

What are the recommendations for FISS surgery

Answer 4

Advanced imaging is extremely useful for assessing tumor invasiveness into surrounding structures and for surgical and radiation therapy planning

Agressive wide resection should include at least:
- 5-cm lateral surgical margins
- two uninvolved fascial layers deep
- +/- resection of bony structures (e.g., removal of the dorsal processes of vertebrae)