Page 1080 - Problem-Based Feline Medicine

1072 PART 13 CAT WITH SKIN PROBLEMS

Vaccine-associated sarcoma arises in the area of vac- ● Adjuvant chemotherapy has been recommended
cination, usually in the interscapular space in the dor- but has not been shown to be beneficial.
sal subcutaneous tissue.
Cats with multicentric fibrosarcomas can only expe-
Fibrosarcomas are usually not painful. rience temporary palliation.
● Surgery cannot be expected to cure these cats.
Tumors may occur anywhere on the body, with 50%
occurring on limbs and 25% on the head and neck. Cats with vaccine-associated sarcoma are also more
difficult to treat.
Diagnosis ● Recurrence and metastasis has been reported after
surgery.
Cytological examination of fine-needle aspirates ● Combinations of surgery, external beam radia-
demonstrates mesenchymal cells with malignant char- tion and chemotherapy show promise in control-
acteristics. This suggests fibrosarcoma. ling these very aggressive tumors.
Definitive diagnosis requires histopathological evalu-
ation of properly acquired biopsy material.
Prognosis
● Care must be taken to perform the biopsy, so the
entire biopsy site may be removed with the tumor at The prognosis is good for solitary fibrosarcomas in
the time of resection. adult cats where complete surgical excision has been
performed.
There is usually an inflammatory component to the
● The ability to completely excise the mass depends
histology of vaccine-associated sarcoma, with pre-
on the tumor location, tumor size and expertise of
dominantly lymphocyte and macrophage populations.
the surgeon.
Histological grading including determining the
Histological grade including mitotic index may help
mitotic index, derived from evaluating ten high-power
predict survival following surgery, and cats with high-
fields, may add prognostic information.
grade tumors should be followed more closely or may
Regional radiography may help determine the local be given adjuvant therapy.
tumor stage and direct surgical planning.
The prognosis is poor with multicentric fibrosarcomas.
Thoracic radiography and regional lymph node
Vaccine-associated sarcoma is associated with a
cytology are required for staging although metastasis is
variable prognosis with often disappointing out-
rare for cats with solitary fibrosarcoma.
comes even with wide excision.
Cats with viral multicentric fibrosarcoma will be FeLV
positive.
Prevention
Differential diagnosis
The Vaccine-Associated Feline Sarcoma Task Force
Fibromas and old wounds with abundant fibroplasia (VAFSTF) was formed to address this evolving and
can have similar cytological appearance on fine-needle important issue and can be found at http://www.
aspirates. avma.org/vafstf/default.htm on the Internet.
Other names are given to these soft tissue sarcomas The VAFSTF has made a number of recommendations:
such as spindle cell tumors, neurofibrosarcomas or ● Cats should not be vaccinated unnecessarily.
nerve sheath tumors. – Rabies vaccines licensed for every 3 years
should not be given yearly and strictly indoor
Treatment cats should not be vaccinated for FeLV.
● Vaccines should not be given in the interscapular space.
Wide surgical excision is the treatment of choice. – It is suggested that the rabies vaccines are given
● Tumor margins should be evaluated histologically on the right hindlimb and the FeLV be given on
for completeness of resection. the left hindlimb.