Lecture 17 2/20/25 Flashcards
How does primary bony neoplasia differ from secondary bony neoplasia?
primary: arises directly from the bone
secondary: spreads from an adjacent site
How does monostotic neoplasia differ from polyostotic neoplasia?
monostotic: lesion affecting a single bone
polyostotic: lesion affecting more than one bone
What is the clinical presentation of bony neoplasia?
-history of progressive lameness
-local, firm, painful swelling
-older, large to giant breed dogs
What are the diagnostics done for bony neoplasia?
-CBC/chem/UA
-cytology
-biopsy
-thoracic imaging: CT or rads
-lymph node aspirates/cytology
What are the characteristics of cytology for bony neoplasia?
-require heavy sedation
-16 to 22 gauge needle
-more successful using ultrasound guidance
-want to sample close to center of lesion
-overall accuracy of 70%; higher with neoplastic process
What are the characteristics of biopsy for bony neoplasia?
-requires general anesthesia
-done with Jamshidi needle or michele trephine
-risks include pathologic fracture and non-diagnostic sample
-80-90% accuracy
What are the characteristics of osteosarcoma?
-most common primary bone neoplasm
-accounts for 85-95% of skeletal neoplasms
-primarily affects appendicular skeleton; can see in axial skeleton and visceral organs
What is endosteal osteosarcoma?
-most common form
-arises from medullary cavity
What is periosteal osteosarcoma?
-arises from periosteum
-can invade into medullary cavity from periphery and cause bony lysis and reactive bone formation
What is parosteal osteosarcoma?
-arises from periosteum
-forms an expansile mass that surrounds cortical bone WITHOUT invading it
-least aggressive form
What is the signalment for osteosarcoma?
-middle-aged
-increased height and weight
-no obvious sex predilection
-indication of higher risk w/ early spay/neuter
-predisposed breeds:
–great dane
–greyhound
–rottweiler
–saint bernard
–doberman
–scottish deerhound
–golden retriever
What are the common locations for osteosarcoma?
-distal radius**
-distal femur
-proximal tibia
-proximal humerus**
What are the radiographic findings in osteosarcoma?
-cortical lysis
-periosteal reaction
-extension of osteogenesis into adjacent soft tissues
-loss of trabecular pattern in metaphyseal bone
What percent of osteosarcoma patients already have metastasis at time of presentation?
15%
What are the prognostic indicators for osteosarcoma?
-age: young dogs have more aggressive disease/worse prognosis
-body weight: smaller dogs have increased survival time
-metastasis: poorer prognosis
-elevated ALP: may indicate increased tumor burden
What are the three surgery options for osteosarcoma treatment?
-total limb amputation +/- hemipelvectomy or scapulectomy (most common)
-limb sparing surgery or fracture repair of pathologic fracture (risks infection, implant failure, and local recurrence)
-partial amputation and endoprosthesis
What are the characteristics of stereotactic radiosurgery as an osteosarcoma treatment?
-done following surgery
-not an effective treatment on its own
-not readily available
-increases risk of pathologic fracture
What are the characteristics of palliative radiation therapy as an osteosarcoma treatment?
-increases comfort in patients with inoperable tumors
-reduces pain/inflammation to improve QOL
-less expensive
-more readily available
What is the standard of care for osteosarcoma treatment?
amputation + chemo
Why is chemo used in addition to amputation?
to increase survival time
What are the components of conservative osteosarcoma treatment?
-analgesia, including NSAIDs, gaba, tramadol, amantadine, and/or tylenol w/ codeine patches
-bisphosphonates to decrease bone resorption by inhibiting osteoclasts
What are the survival times by osteosarcoma treatment?
-amputation alone: 3 to 6 months
-amputation + chemo: 12 to 14 months
-radiation alone: 4 to 10 months
-conservative: 1 to 3 months
What are the characteristics of osteosarcoma in cats?
-most common primary bone lesion in cats, but not common overall
-middle aged to older cats
-no sex or breed predilection
-lower metastatic rate
-treated with amputation
-MST with treatment of 11 to 49 months
What are the characteristics of chondrosarcoma?
-second most common appendicular primary bone neoplasm (5-10% of cases)
-lower metastatic rate
-often metastasizes to axial skeleton
