Tumors of Appendicular & Axial Skeleton Flashcards
Small dog OSA has a predilection for ________
Axial skeleton (vs appendicular)
What age do dogs commonly get OSA?
Bimodal - 1-2 yrs (young) or 7-9 yrs
What dog breeds are more at risk for getting OSA?
- Large/Giant breeds
- Rotties
- Great danes
- Irish wolfhounds
- Greyhounds
- Males/Rotties neutered before 1 yr of age
Most common presenting complaint with OSA?
- Lameness
- Localized limb swelling
- Occasionally pathological fracture
Ddx list for a neoplastic primary bone tumor?
- OSA OSA OSA
- Chondrosarcoma
- Fibrosarcoma
- Hemangiosarcoma
Most common locations for OSA of the appendicular skeleton?
1. Distal radius
2. Proximal humerus
3. Distal femur
4. Proximal tibia
Away from the elbow, towards the knee
Osteosarcoma in dogs favors development in the ________ of bone
A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Intracapsular space
C. Metaphysis
(Usually diaphysis in cats although rare)
What presents similarly and must be ruled out when diagnosing osteosarcoma?
Fungal infection (Coccidio, Blasto)
Fungal dogs usually present systemically ill
True or False: LN aspirate is always indicated when working up and staging OSA in a dog
False - spreads hematogenously not through lymphatics, 5% incidence of mets to LNs
How to work up and stage for OSA of the appendicular and axial skeleton?
- CBC/Chem - if inc. ALP = BAD (but non specific to OSA)
- FNA cytology with ALP staining > biopsy
- Full body CT > Rads bc 90% micrometastasis that can’t be seen on rads
- Nuclear scintigraphy (bone scan) to look for bone to bone mets
- Limb rads
Radiographic appearance of OSA?
- Mixed lytic to blastic appearance
- Palisading sunburst effect
- Codmans triangle
- Does NOT cross joint space
- Pathologic fracture
- Can’t tell border between normal & abnormal
Why doesn’t OSA cross the joint space?
- Cartilage provides barrier due to collagenase inhibitors which inhibits tumor invasion
(If crossing joint space, more likely a synovial cell sarcoma
List indications for limb salvage when treating OSA in dogs
- Severe osteoarthritis
- Neuro disease
- Morbid obesity
(when surgical amputation isn’t indicated)
Contraindications to limb salvage for treatment of OSA?
- Inappropriate location of tumor
- Large lesion > 50% of diaphysis
- Pathologic fracture
- Advanced disease
- Poorly compliant owner
- Extensive ST involvement
List the anatomic sites where Limb salvage surgery for OSA can be done
- Distal radius
- Distal ulna
- Digit or metacarpus/tarsus
- Scapula
Gold standard treatment option for OSA? What is the exception?
Limb amputation + chemo (Carboplatin)
EXCEPTION: Proximal femoral lesion - requires more aggressive sx - En block acetabulectomy or hemipelvectomy
Palliative care with analgesics for treatment of OSA has what prognosis?
MST of 1-3 months
What is the MST of OSA in dogs (dependent on tx)?
- Palliative care: 1-3 months
- SRS (Radiation): 4 months
- Surgery alone: 6 months
- Surgery + chemo (Carboplatin): 1 yr
KNOW ALL
Although rare, Osteosarcoma in cats favors development in the ________ of bone
A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Intracapsular space
B. Diaphysis
(metaphysis in dogs)
Gold standard tx for OSA in cats?
- Amputation alone can be curative w/o chemo (less aggressive unlike dogs)
- Amputation + chemo if proximal humerus lesions
Chemo of choice for OSA?
Carboplatin
What palliative therapeutic options are available for treatment of OSA?
- NSAIDs
- Biphosphonates (Zoledronate + Pamidronate (osteoclast inhibitors)
- Radiation therapy
Osteolytic lesions in multiple areas surrounding the joint space is more likely a __________ than OSA
Synovial cell sarcoma
What can be used for bone biopsy to work up and stage a bone tumor?
- Jam shedi (preferred) inserted into medullary cavity
- Michele Trephine (much higher risk of pathologic fracture)
What procedure is performed for OSA of the distal radius?
- Surgical excision of distal radius, replaced with implant and pancarpal arthrodesis (fusing radius and carpal bones
What complications can arise from limb salvage surgery for removal of OSA?
- Infection most commonly (50% of cases)
- Implant failure
When considering stereotactic radiosurgery for treatment of OSA, what is the best site for this use?
Proximal humerus best site for SRS (low fracture rate)
What complications can arise from using stereotactic radiosurgery for treatment of OSA?
- Radiation caused bone fractures in 1/3 of cases
best used for OSA of the Proximal humerus
What tumor location typically indicates a worse prognosis for patients with OSA?
Proximal humerus lesion has a shorter MST
A Rottie presenting with right forelimb lameness and swelling around the metacarpus. You suspect OSA. What can be seen on CBC/Chem to help lean towards OSA?
- Elevated ALP (indicates poor prognosis)
