DM2 Pt5-3 Feline Injection Site Sarcoma (FISS) Flashcards
What were feline injection site sarcomas (FISS) originally called?
They were originally called “vaccine site-associated sarcomas.”
When were feline injection site sarcomas first reported, and which vaccine was initially linked?
They were first reported in 1991 and linked to rabies vaccination.
Why were FISS renamed from vaccine site-associated sarcomas?
Because they can occur after any injection, not just vaccines, including antibiotics and corticosteroids.
What is one significant risk factor for developing FISS?
The number of injections at a site; 3-4 vaccinations in the interscapular region doubles the risk.
How does the temperature of a vaccine affect the risk of FISS?
Administration of cold vaccines increases the risk compared to room temperature vaccines.
Does the brand or manufacturer of the vaccine increase the risk of FISS?
No, vaccine brand or manufacturer is not associated with increased risk.
Does re-using disposable syringes increase the risk of FISS?
No, re-using disposable syringes is not associated with increased risk.
Does shaking multidose vials or massaging the area post-vaccination increase the risk?
No, neither shaking vials nor massaging the area increases the risk of FISS.
What is the primary treatment challenge for interscapular FISS?
Interscapular FISS are challenging to treat due to their aggressive nature.
What diagnostic tests are recommended for assessing FISS?
Full haematology, biochemistry, FeLV/FIV status, urinalysis, and biopsy are recommended. Cytology is not reliable.
How long should inflammatory reactions post-injection resolve?
Inflammatory reactions should resolve in 6–8 weeks.
What is required to definitively diagnose FISS?
A biopsy is required to definitively diagnose FISS.
What imaging techniques are recommended for staging FISS?
Thoracic CT or three-view inflated thoracic radiography to check for metastases.
Where does FISS most commonly metastasize?
The most common site for metastasis is the lungs, but it can also spread to liver, lymph nodes, and subcutaneous tissue.
What are the recommended surgical margins for FISS excision?
3–5 cm lateral margins with two muscle layers or bone as the deep margin.
Why is the first surgery critical in treating FISS?
The first surgery is the most effective for curative treatment.
What complications may occur after radical surgery for FISS?
Complications include wound dehiscence and seroma.
What are the key components of postoperative care after radical FISS surgery?
Support dressing, multimodal analgesia (opiates, NSAIDs, local anesthesia), suction drains, and assisted feeding.
What are the factors that influence prognosis in FISS treatment?
Factors include location of FISS, clean vs dirty margins, number of surgeries, surgeon experience, tumor grade, and metastasis development.
Why is recurrence common even in cases with clean surgical margins?
Due to the infiltrative nature of the tumor and potential ongoing inflammation leading to further tumorigenesis.
What is the tumor recurrence rate in FISS cases with histopathological clean margins?
Recurrence rates in cases with clean margins range from 14–50%.
When is radiotherapy used in FISS treatment?
Radiotherapy is used as an adjuvant therapy postoperatively or preoperatively to treat microscopic disease.
Why might tumor cells become more resistant to radiotherapy after surgery?
Surgery can damage blood supply to tumor cells, making them more radioresistant.
Is chemotherapy proven to be effective in treating FISS?
The efficacy of chemotherapy is unproven, though it is used due to the high metastatic rate of FISS.
What is the recommended treatment for small FISS tumors?
Wide excision after incisional biopsy, with or without radiotherapy.
What is the recommended treatment for larger FISS tumors?
A combination of surgery, radiotherapy, and possibly chemotherapy.
What task force was created in response to the appearance of FISS?
The Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) in North America, 1996.
What region do AAFP and WSAVA recommend avoiding for vaccine administration?
The interscapular region should not be used for vaccinations.
Where does the AAFP recommend vaccines be administered in cats?
The distal limbs.
Where does the WSAVA recommend vaccines be administered in cats?
The lateral abdomen or thorax, changing the site of administration each time.
What is the recommended vaccination frequency for FHV, FCV, and FPV according to WSAVA and AAFP?
Every 3 years, although many practitioners in the UK still vaccinate annually.
How often is FeLV vaccination recommended for older cats according to the ABCD?
Every 2–3 years, depending on risk.
Why is vaccination at the stifle level in the hind limb preferred over the interscapular region?
It allows good surgical margins with amputation if an injection site-associated sarcoma develops.
What drugs, besides vaccines, have been associated with injection site-associated sarcomas?
Long-acting corticosteroids and long-acting penicillins.
What types of injections besides vaccines have been linked to FISS?
Long-acting antibiotics and steroids.
What is the most important component of treatment for FISS to ensure prolonged disease-free intervals?
Radical surgical excision.
When should adjunctive radiotherapy and chemotherapy be considered for FISS treatment?
For large grade 3 tumors where surgery alone is unlikely to be curative.
