Injection Site Sarcomas

Question 1

Describe the biologic behaviour of injection site sarcomas:

Answer 1

• Very locally invasive w/ finger like projections
• Metastatic rate of 20-25%

Question 2

What two vaccines are most implicated in FISS?

Answer 2

FeLV and Rabies vaccine

Question 3

What are three features of a FISS on biopsy that increase suspicion over just a normal sarcoma?

Answer 3

• Necrosis
• Inflammation
• Increased mitotic figures

Question 4

What is the 1,2,3 for biopsy of a FISS?

Answer 4

• 1 - still growing after 1 month
• 2- larger than 2cm
• 3 - still present after 3 months

Question 5

For FISS what is the time to recurrence with:

1. Conservative surgery
2. Radical surgery
3. Surgery w/clean margins

Answer 5

1. 2 months
2. 9 months
3. 16 months

Question 6

What are the four rules of feline vaccine injection site selection with concern to FISS?

Answer 6

1. Any vaccine containing rabies antigen in the right pelvic limb (rabies is right)
2. Any vaccine containing FeLV antigen in the left pelvic limb (L is for left)
3. Feline rhinotracheitis and panleukopenia vaccines (FVRCP) in the right shoulder
4. Give all vaccines as distally in the limb as possible