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27 Cards in this Set
- Front
- Back
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Osteosarcoma
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Osteoblast lay down matrix and become bone
malignancy of osteoblast most common primary bone tumor in dogs appendicular skeletal OSA most common axial skeletal OSA and extraskeletal OSA less common but equally aggressive |
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Other bone tumors
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Osteosarcoma #1 (85%)
chondrosarcoma, multilobulat osteochondroma, fibrosarcoma, hemangiosarcoma Soft tissue OSA rare: mammary, SQ, spleen |
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Signalment for OSA (IMPT)
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dog highest incidence
giant breed: st. bernard, rottie, gret dane, grey hound age of onset bimodal: 7-10yr (geratric) and 2yr (genetic link) |
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predilection site of osteosarcoma
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75% appendicular
metaphysis (away from elbow near the knee) 4 sites- distal and proximal tibia, distal radius, proximal humerus, distal femur 25% axial skeleton |
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what cause pain in OSA and Differentials for lameness
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most pain due to extension of tumor within marrow cavity and lameness cause pain, can see bulge of bone, push on soft tissue, so more pain
cruciate injury (often treat with NSAID but relaspe and more painful) |
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Signalment of OSA (KNOW)
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breed
age site of predilection ( long bone, metaphysial region, away from elbow towards knee) |
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Risk factor for development of OSA
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1. Ionizing radiaiton
2. Bone infarcts 3.larger breed dog more prone to microfracture trauma and chronic trauma serve as irritation and can lead to cancer formation 4. previous fractures and metallic impants. |
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PE, history and clinical sign of OSA
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lameness +/- acute
+/- palpable/ visible mass soft tissue inflam sometimes history of trauma e/d ok weight bearing or non- wt bearing partial response of NSAIDs Age, breed, predilection site IMPT |
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Hx and clinical sign of OSA in axial skeleton
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not weight bearing so no weight bearing lameness
difficulty breathing in chest wall maxilla osteosarcoma (difficulty eating) |
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pulmonary mets
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often present with lamemess and pain only but initially don't see pulmonary mets, 80-90% develop pul mets so do chemo anyway if chest rads clear
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Prognostic factors for OSA
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young= bad
detectable mets lesion @ ddx= bad elevated ALP= bad % necrosis= higher is better after tx larger tumor= earlier mets histo grade, higher grade, shorter survival increased tumor microvascular density, -ve prognosis location of tumor: mandibular OSA= long survival, soft tissue OSA- very poor prognosis infeciton in allograft- survive longer |
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Ddx and staging of OSA
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Min. database to screen for concurrent dz and ALP
rads: bony proliferation and lysis i metaphysial region of long bone thoracic rads: gross mets in less than 10% at ddx but still do chemo cause 90% develop pul mets if surgery alone Biopsy GOLD STANDARD FNA may provide ddx and less invasive |
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rads on osteosarcoma
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radiological appearances VARIES
typical= bony lesion +/- osteolysis, osteoproliferation and remodeling Bone changes doesn't mean osteosarcoma (85-95%), need cytology or histology to ddx frequent extension to soft tissue codman's triangle not pathognomonic to osterosarcoma gerenally DOES NOT cross joint (can be synovial cell sarcoma, bacterial or fungal osteomyelitis) occaionally pathological fracture ddx |
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codman's triangle
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The interface between a growing bone tumor and normal bone, appearing in an x-ray as an incomplete triangle formed by the periosteum.
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Biopsy for osteosarcoma
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Invasive and painful for excisional biopsy
coring thru bone and get a piece of bone by Jamshidi or trephin Aim at center of lesion cause body trying to wall it off and get reactive bone instead If early lesion, never can push 18G needle thru strong bone so cannot do cytology (even though less invasive) Jamshidi preferred, painful, might not use leg days after |
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Cytology
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can see sarcoma but can be osteosarcoma, chondrosarcoma or fibrosarcoma, so do ALP stain, only stain osteosarcoma
FNA- often provide ddx with large immature mesenchymal cells that may have intracytoplasmic or extracellular osteoid) FNA can alsorule out fungal and bacterial osteomyelitis |
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Diagnosis of osterosarcoma (cont)
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every ddx never 100% (may get reactive bone)
after ddx of osteosarcoma, need staging (LN aspirate- uncommon site of mets , min database- mostly non specific, Chest rads impt- common site of mets) |
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Therapy
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radical surgery and chemo
if just amputate w/o chemo: palliative, dog will be comfortable but die of pul mets amputation alone (4-5 mths), w/ chemo (10-14 mths) |
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Surgical opetion for appenidicular OSA
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amputation or limb- sparing procedure
RT: admin corase fraction , improvee limb function and quality of life for 2-4 mths, best way to control pain chemo: do after amputation to prolong survival time, 15% cure of dz |
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Chemo
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once mets is clinically detectable, chemo is usually ineffective
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Palliative tx
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NSAID, opiods, bisphonates
esp for those cannot be amputate |
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Feline OSA
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rare in cats
older cats 2/3 appenicular more commonly hind limb favorable prognosis with amputation alone!!!! MST: 2-3 yrs |
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Canine axial osteosarcoma
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medium to large breed most common
middle aged female more common unlike large breed dog, OSA in small dog tend to affect axial skeleton |
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Histroy and PE of axial OSA
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most common: mandible and mazilla
less common: spin, ribs, nasal and cranium clinical signs depend on location: visible palpable mass, dysphagia, pain when opn mouth, exophthlmia, ptyalism, epistaxis, paraparesis, dyspena/ tachypnea |
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ddx of axial OSA
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similar to appendicular OSA
Myelogrphy may be indicated to further delineate spinal tumor biopsy and FNA required |
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Bio behavior, prognosis and tx for axial OSA
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bio behavior depend on site, mandibular less likely to mets
tx: surgical resection followed by chemo EXCEPT madibular OSA, surgery alone provide up to 1 yr survival ribs with highest rate of mets, just like appendicular OSA palliative therapy for pain relieve esp if non- resectable |
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Extraskeletal OSA
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rare, most commonly spleen and other soft tissue
locally invasive and high mets |
