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166 Chondrosarcoma

• Metastatic bone tumors: transitional cell, • Histopathologic evaluation is required to 10-15 mg/kg PO q 8-12h; amantadine
3-5 mg/kg PO q 24h.
prostatic, mammary, thyroid, anal sac confirm the diagnosis of CSA. ○ Pamidronate (1-2 mg/kg diluted in saline
VetBooks.ir • Tumors that locally invade adjacent bone: able tumors, an incisional biopsy is IV over 2 hours) and zoledronate (0.1 mg/
apocrine gland carcinomas
○ For nasal tumors and large, nonresect-
nasal carcinoma; oral tumors (squamous
kg diluted in saline IV over 15 minutes)
recommended. For resectable tumors, an
cell carcinoma, melanoma, fibrosarcoma,
mineral density and can reduce the pain
but it is reasonable to surgically remove
ameloblastoma), synovial cell sarcoma, incisional biopsy is not contraindicated, are bisphosphonates that increase bone
histiocytic sarcoma, digital tumors (squamous all local disease, with biopsy submission associated with bone tumors. They have
cell carcinoma, melanoma) after surgery. been studied most thoroughly for the
• Hematopoietic tumors: myeloma, lymphoma. treatment of osteosarcoma (p. 726).
Radiographic lesions typically are purely TREATMENT ○ Palliative RT effectively controls the
lytic. pain associated with bone tumors. Most
• Bacterial or fungal osteomyelitis Treatment Overview information regarding efficacy is from the
Additional differentials for epistaxis (p. 1221) Nasal CSA, like most other nasal tumors, is treatment of osteosarcoma, but similar
most effectively treated with radiation therapy benefits are seen in patients with CSA.
Initial Database (RT). For CSAs arising in other locations, ○ Patients with pulmonary metastasis or
• Radiographic imaging of the primary tumor surgery is indicated whenever possible. Palliative nasal congestion often benefit from anti-
○ The aggressive bone changes associated therapy, which focuses on controlling pain and inflammatory doses of oral glucocorticoids
with CSA are the same as those seen with other associated clinical signs, is recommended such as prednisone 0.5-1 mg/kg PO q 24h
osteosarcoma (p. 726). for advanced-stage tumors or when definitive (do not combine with NSAIDs).
○ Nasal neoplasia is most often associated therapy is declined.
with soft-tissue opacity in the nasal Recommended Monitoring
cavity and/or frontal sinuses, as well Acute General Treatment Patients should be evaluated every 2-3 months
as destruction of the turbinates, nasal • Treatment of nasal CSA (p. 680) with a physical examination. Thoracic radio-
septum, vomer, or surrounding palatine, • The treatment of choice for rib CSA is graphs should be performed every 4-6 months.
maxillary, and/or frontal bones. wide surgical resection. Multiple ribs and/ Imaging of the site of the primary tumor may be
○ Primary rib tumors often can be distin- or underlying lung may need to be removed. indicated, depending on location, completeness
guished from tumors originating from the Prosthetic mesh may be needed for thoracic of excision, and clinical signs.
lung by the presence of an extrapleural wall closure, and diaphragmatic advancement
sign, characterized by a smoothly margin- techniques may be necessary for caudal PROGNOSIS & OUTCOME
ated indentation of the lung that tapers thoracic tumors.
gradually at the junction of the thoracic ○ Adjuvant RT is recommended if excision is Nasal CSA: distant metastasis is uncommon.
wall. incomplete, but there is little information • With conventional RT, median survival
• After a radiographic or histologic diagnosis, regarding efficacy. is ≈15 months. Patients with nasal CSA
patients should be completely staged with • The treatment of choice for appendicular are 3.3 times less likely to have local
a CBC, chemistry panel, urinalysis, and CSA is amputation. Limb-sparing techniques recurrence than are patients with nasal
three-view thoracic radiographs. can be considered for tumors arising from carcinomas.
the distal radius, distal ulna, or proximal • For patients with nasal tumors in general,
Advanced or Confirmatory Testing femur. extension into the frontal sinuses and/
• For axial tumors, CT imaging is recom- • For CSA arising from other sites, wide or erosion through the bones of the nasal
mended to more accurately stage local surgical excision is recommended whenever passage is associated with a 2.3-fold increase
disease and help with planning surgery and/ possible. When excision is incomplete, in risk of local recurrence. Unilateral versus
or radiation therapy. CT imaging can be adjuvant RT may help improve local control, bilateral involvement is not a significant
done in place of radiographic studies. but there is limited information regarding prognostic factor.
○ For nasal tumors, CT is superior to radio- efficacy. Stereotactic RT has not been evalu- • There is limited information regarding
graphs for detecting soft-tissue opacity ated for CSA. However, based on experience prognosis with stereotactic RT, but it likely
within the nasal cavity and surrounding with osteosarcoma (p. 726), it should be is similar or better compared to conventional
sinuses, bony destruction, and extension considered for nonresectable CSA. RT.
through the cribriform plate into the • There is no information regarding the efficacy • With palliative care alone, survival times are
brain. of chemotherapy for the treatment of CSA; ≈3 months.
○ If a patient is undergoing CT, concurrent it is not routinely recommended. Non-nasal CSA:
imaging of the lungs is recommended • Palliative care is indicated for patients with • 15%-30% develop metastatic disease (lungs
as a more sensitive way to screen for advanced local disease or visible metasta- most common).
pulmonary metastasis. sis and when owners decline definitive • With aggressive surgery, median survival is >
• For accessible tumors, fine-needle aspiration therapy. 3 years, and many dogs will enjoy long-term
(FNA) for cytologic evaluation is a minimally ○ Nonsteroidal antiinflammatory drug local control. However, depending on tumor
invasive procedure that can help support a (NSAID) choices include aspirin 10-25 mg/ location and completeness of excision, up to
diagnosis of CSA. kg PO q 8-24h; carprofen 2 mg/kg PO q 40% will develop local recurrence.
○ FNA can be considered for lesions with 12h; deracoxib 1-2 mg/kg PO q 24h, may • With palliative care alone, survival times of
associated bony cortical destruction. use 3-4 mg/kg PO q 24h for first 7 days > 1 year are still possible depending on tumor
Ultrasound guidance can be used to aid only; meloxicam 0.1 mg/kg PO q 24h; or location, patient clinical signs and comfort,
sample collection. firocoxib 5 mg/kg PO q 24h. and rate of tumor growth.
○ Alkaline phosphatase cytochemical analysis ○ Other oral analgesic drugs include acet-
on FNA samples is recommended. Alkaline aminophen with codeine (never in cats) PEARLS & CONSIDERATIONS
phosphatase is a highly sensitive and fairly (Tylenol #4 = 300 mg acetaminophen,
specific marker for osteosarcoma, and a 60 mg codeine) 0.5-2 mg/kg PO q 6-8h, Comments
positive result would make a diagnosis of with dosing based on codeine; tramadol Chondroblastic osteosarcoma can resemble
CSA less likely. 2-5 mg/kg PO q 6-12h; gabapentin CSA on small biopsy samples. Whenever

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