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RUSVM SAM 2 > Appendicular And Axial - OSA > Flashcards

Appendicular And Axial - OSA Flashcards

1
Q

What is the most common primary bone tumor in dogs and cats?

A

Osteosarcoma
Dogs> cats

Appendicular >axial

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2
Q

Signalment for OSA

A

Large to giant breeds (size and height are prognostic)

Male neutered (esp rotties) —> 1 in 4 early gonadectomized Rotties have lifetime risk of OSA

Bimodal age distribution: 1-2yrs and 7-9yrs

Small dog OSA has predilection for axial skeleton

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3
Q

What are some of the proposed etiologies of OSA?

A

Hormonal
Genetic
Repetitive micro-trauma

Molecular factors
-MET, Trk and HER-2 —> all encode TK receptors and control growth/proliferation of cells

Aberrant/excessive insulin like GF
Aberrant signaling through mammalian target of rapamycin (mTOR) pathway
Presence of telomerase

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4
Q

Presenting complaint with OSA

A

Lameness and localized limb swelling

—> lameness caused by periosteal inflammation, microfractures, and occasionally pathologic fracture

—> swelling- extracompartmental extension of tumor into adjacent soft tissue

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5
Q

DDX for appendicular skeletal masses

A

OSA

Chondrosarcoma
Fungal — usually systemically ill

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6
Q

Two most common sites for OSA?

A

Distal radius (23%)

Proximal humerus (18%)

Favor development of metaphyseal region of bone

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7
Q

What re the 3 basic types of OSA?

A

Endosteal (most common)

Periosteal
Parosteal
—> rare = originate from the periosteal surface and rarely involve the endosteum/medullary canal

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8
Q

You do a CBC/chem on your OSA dog, it shows an elevated ALP… what does this indicate?

A

Negative prognosis

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9
Q

How sensitive are thoracic metastasis checks at time of diagnosis?

A

90% of dogs will have micrometastatsis and diagnosis but <15% of these will have clinically detectable mets at time of initial diagnosis

Localized imaging — two view radiographs of affected limb

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10
Q

How do OSA appear on radiographs?

A

Lytic and blasting lesions
Loss of cortical bone
Periosteal proliferation
Palisading cortical bone (sunburst effect)

Codmans triangle= periosteal lifting caused by sub periosteal hemorrhage

Loss of the fine trabecular pattern in metaphyseal bone
Pathological fracture with metaphyseal collapse

Does NOT cross joints

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11
Q

T/F: biopsy is the preferred method for diagnosis of OSA

A

False

FNA/cytology —>

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12
Q

What two tools can be used for bone biopsy? What are the benefits/ downfalls of these?

A

Jam shedi —> 82% accuracy of diagnoses

Michele trephine —> large samples with diagnostic rate of 94%, but higher rate of pathological fracture

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13
Q

What is the gold standard for local control of OSA?

A

Limb amputation

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14
Q

What will you do for local control of OSA if the lesion is at the proximal femoral head?

A

More aggressive sx required

—> en block acetabulectomy or subtotal hemipelvectomy

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15
Q

What are indications for limb salvage in OSA cases?

A

Severe osteoarthritis
Neurologic disease
Morbid obesity

Reluctance of owners to proceed with amputation

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16
Q

Contraindications of limb salvage with OSA?

A

Large lesions > 50% of diaphysis
Extensive soft-tissue involvement
Pathological fracture

Poorly complaint owner or patient
Advanced disease

Inappropriate location of tumor

17
Q

What are OSA sites that allow for limb salvage surgery?

A

Distal radius — most common site of tumor

Distal ulna - ulnectomy

Digit or metacarpus/tarsus - amputation

Scapula - partial scapulectomy

18
Q

When doing limb salvage procedure on the distal radius should be transacted _______cm proximal to the tumor

A

3-5

19
Q

T/F: Distal radius OSA limb salvage are often reconstructed with endoprothesis

A

True

20
Q

What re the complications for limb salvage surgery?

A

Complication rate >50%

Implant failure - 40% of cases
Local tumor recurrence 10-28% (cn be reduced with local chemo agents)

Infection occurs in more than 50% of cases and approx 2/3rd of infections are diagnosed >6months after surgery

21
Q

T/F: stereotactic radiation therapy limb salvage offers greater survival time compacted to surgical treatment

A

False

No advantage

22
Q

Complications form stereotactic radiation therapy for OSA?

A

Mild skin effects

Fracture of radiated bone (36%).

23
Q

What is the best site for SRS based on low post radiation fracture rate?

A

Proximal humerus

24
Q

OSA have a 90% met rate, how do you control this systemically?

A

Chemo recommended in all cases of OSA

**Carboplatin **
Cisplatin
Doxorubicin

All platinum-containing protocols result in similar survival times

25
Q

Protocol for carboplatin treatment?

A

4 treatments

Monitor CBC and renal fxn

26
Q

What palliative therapeutic options are available for OSA?

A

Synthetic analog of pyrophosphate (amino-bisphosphonates)

—> inhibit osteoclastic bone reabsorption

27
Q

What is the MOA of amino-bisphosphonates ?

A

Exert their effect on osteoclasts via inhibition of the mevalonate pathways which disrupts intracellular signaling and induction of apoptosis

  • inhibit proliferation, angiogenesis, MMP
  • immunomodulatory
  • effect on cytokine and growth factors
28
Q

How effect does palliative radiation therapy have >

A

Reduced local inflammation, minimizes pain, slows progression of metastatic lesions and improves QOL

29
Q

What is the median duration of response to palliative radiation therapy?

A

73-130days

Better when there is less than 50% of bone involved and located in proximal humerus

30
Q

What analgesic options can you give if managing OSA palliatively?

A

NSAIS
Opioids
NMDA antagonsit
Anticonvulsant

31
Q

What re the indications for pulmonary metastatectomy?

A

Development >300days after initial diagnosis

< than 3 radiographically evident met lesions

No doubling of size of lesions or development of new lesions in a 4 week period

Palliative relief for hypertrophic osteopathy

32
Q

What is the prognosis of OSA

A

Palliative

  • analgesia MST 1-3months
  • RT MST 4-10monts

Surgery alone MST 4-6months
Chemo alone - limited data

Surgery with chemo MST 8-12months

33
Q

What are prognostic factors for OSA?

A

Body weight: worse prog if >40 kg

Age: worse if <7 or >10yrs

Tumor site: worse if proximal humerus (usually larger in size before diagnosis)

Tumor volume: worse when large

Histologic grade: grade 1 OSA (4%), grade II (21%), grade III(75%)

ALP —> for every 100 U/L increase in total ALO increased risk of tumor related death by 25%

34
Q

T/F: Feline OSA is more common in the diaphysis than the metaphysis

A

True

35
Q

Feline OSA are most commonly located where?

A

Pelvic limb > thoracic

Diaphysis

Often less aggressive and lower met rate than dog

36
Q

MST in cat with OSA

A

Amputation alone may be curative in cats with OSA

MST 29-49months

RUSVM SAM 2 (44 decks)

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