Biologic Behaviour

•CSA is a malignant cartilage-producing neoplasm arising de novo within bone

•CSA is the 2nd most common primary bone tumor (5%-10%), but uncommon in the appendicular skeleton

•CSA should be differentiated from chondroblastic OSA

•etiology is unknown but can arise at multiple cartilaginous exostoses sites or previous bone lesion

•median age 8.7 years

•breed predisposition: Golden Retriever

•61%-91% CSA occur in the axial skeleton (i.e., nasal cavity [26%-36%], ribs, pelvis, vertebrae, and skull)

•other CSA sites include the appendicular skeleton (<20% to 26%), digits, os penis, and extraskeletal sites (i.e., mammary gland, heart valves, aorta, larynx, trachea, lung, and omentum)

•CSA is slow to metastasize

Staging

•CSA is classified as primary or secondary:

•primary CSA: de novo tumor unassociated with preexisting lesion)

•secondary CSA: tumor associated with preexisting cartilage lesion (i.e., osteochondroma or multiple cartilaginous exostoses)

•central (i.e., medullary) and peripheral (i.e., periosteum) classification is only applicable to secondary CSA

Treatment

•surgical resection is the preferred treatment for cats and dogs with CSA

•radiation therapy is recommended for unresectable lesions

•chemotherapy is recommended for grade III CSA

•ciprofloxacin, a fluoroquinolone with known toxicity to chondrocytes, inhibits chondrocytic proliferation and induces apoptosis in vitro and may be toxic to CSA cells

Prognosis

•tumor location is prognostic with CSA in the skull, nasal turbinates, and appendicular skeleton having a better prognosis than rib CSA

•MST 210-580 days for dogs with nasal CSA and metastasis is very rare

•MST 1,080 days for dogs with rib CSA

•MST 201-540 days for dogs with appendicular CSA treated with limb amputation ± chemotherapy

•12-month survival time 17% and 24-month survival time 13%

•histologic grade: I, II, and III

•histologic grade is an important prognostic indicator for CSA of the same site