Page 724 - Cote clinical veterinary advisor dogs and cats 4th

338 Fibrosarcoma

DIAGNOSIS • Palliative treatment options, such as pallia- • In certain situations where surgery is not
tive irradiation, may help control pain or indicated (e.g., nonresectable tumors or
Diagnostic Overview
VetBooks.ir Definitive diagnosis can be confirmed only or in patients when definitive treatment be used to provide some degree of tumor
metastatic disease), radiation therapy may
discomfort in patients with advanced tumors
cannot be tolerated.
histopathologically, although additional tests
control.
such as diagnostic imaging are often helpful
in defining the extent of the tumor, especially • Palliative irradiation or metronomic chemo- • Prognosis is excellent for low- to intermediate-
grade fibrosarcomas with appropriate local
therapy (daily low doses of chemotherapy)
for oral fibrosarcomas. may help control the local tumor for treatment. This includes surgical resection
significant periods. with clean histopathologic margins or
Differential Diagnosis • Marginal tumor excision with intralesional incomplete resection combined with radia-
• Other soft-tissue sarcomas chemotherapy beads can result in long-term tion therapy.
• Other skin and subcutaneous tumors (e.g., control and may be considered as an alterna- • Palliative radiation after incomplete tumor
mast cell tumors [p. 628]) tive to radiation for some cases. excision has resulted in tumor control in
• Other oral tumors (e.g., epulis, melanoma, 65% of dogs with soft-tissue sarcomas at 5
squamous cell carcinoma) Acute and Chronic Treatment years.
• Benign or non-neoplastic masses • Aggressive surgical resection, radiation • Metronomic chemotherapy using cyclophos-
○ Benign tumor (e.g., lipoma) therapy, and/or chemotherapy may be used phamide and piroxicam has been shown to
○ Abscess, granuloma for treatment of fibrosarcoma (p. 1451). result in tumor control for a median of more
• Chemotherapy may be indicated for tumors than 400 days after incomplete tumor exci-
Initial Database of the spleen or high-grade tumors. sion of soft-tissue sarcomas.
• Fine-needle aspiration and cytologic evalua- • Information is limited regarding prognosis for
tion may help identify the tumor type before Possible Complications high-grade fibrosarcomas, but it is considered
other diagnostics are considered. Complications of treatment for fibrosarcomas to be guarded based on the increased likeli-
• Three-view thoracic radiographs to rule out depend on the types of treatments and the hood for metastases.
pulmonary metastases location of the primary tumor. • Dogs with splenic fibrosarcomas are more
• Radiographs of the affected area may reveal likely to develop metastases and therefore
involvement of underlying bone. Recommended Monitoring have a poor prognosis.
• Abdominal ultrasound to identify splenic After appropriate local treatment, regular
tumors and rule out metastasis follow-up exams are indicated to monitor for PEARLS & CONSIDERATIONS
• Fine-needle aspiration and cytologic exam of recurrence and metastasis. High-grade tumors
the regional/draining lymph node to assess may require more frequent monitoring for Comments
for metastasis metastases during and after chemotherapy Many animals with fibrosarcoma are success-
administration. fully treated with wide surgical excision of the
Advanced or Confirmatory Testing • Dogs that are likely to develop metastasis tumor. Animals with tumors that are difficult
• Biopsy of mass (splenic tumors, high-grade tumors) should to treat in this manner (e.g., oral sarcomas,
○ Histopathologic confirmation of fibrosar- be monitored closely (q 2-3 months) with a grade 3 sarcomas, nonresectable tumors) should
coma physical exam, lymph node palpation, and be referred for consultation with a specialist
○ Special immunohistochemical stains may thoracic radiographs. (surgeon, oncologist, or radiation oncologist)
be necessary to differentiate fibrosarcoma • Dogs with low- or intermediate-grade tumors to develop a multimodality treatment approach.
from other soft-tissue sarcomas, especially that have adequate local treatment should
poorly differentiated tumors. have physical exams q 2-3 months or more Technician Tips
• CT or MRI (p. 1132) may be necessary frequently, depending on risk of side effects All masses in dogs and cats, even slow-growing
to delineate the local extent of the tumor from treatment. Thoracic radiographs could ones, should be aspirated to rule out malignant
and to plan for surgery or radiation be done less frequently (6 months and 1 year tumors.
therapy. after therapy).
• Histopathologic grade of the tumor is Client Education
necessary for determining the prognosis PROGNOSIS & OUTCOME Pet owners can be educated to monitor their
and treatment of most soft-tissue sarcomas pets for the occurrence of tissue masses such as
(p. 927). • A combination of radiation therapy and fibrosarcomas. Early detection and treatment
surgery has resulted in long-term tumor may allow for less aggressive treatments with
TREATMENT control in 86% of dogs with fibrosarcoma fewer side effects.
in peripheral sites and 54% of fibrosar-
Treatment Overview comas from all sites, including the oral SUGGESTED READING
• Definitive treatment is based on complete cavity. Liptak JM, et al: Soft tissue sarcomas. In Withrow
eradication of the primary tumor whenever • Radiation therapy alone has resulted in SJ, et al, editors: Small animal clinical oncology,
possible. 1-year tumor control rates of only 33% and Philadelphia, 2013, Saunders, pp 356-380.
• Because metastasis is uncommon, additional therefore is not typically recommended for AUTHOR: John Farrelly, DVM, MS, DACVIM, DACVR
treatment such as chemotherapy is rarely fibrosarcomas. However, this statistic may EDITOR: Kenneth M. Rassnick, DVM, DACVIM
used but could be considered for high- underestimate efficacy because it is derived
grade tumors or tumors that have already from studies that used suboptimal radiation
metastasized. dose schedules.

www.ExpertConsult.com