Osteosarcoma & Osteomyelitis

Question 1

What is Osteomyelitis?

Answer 1

infection in the bone tissue- cortical bone and medullary cavity

Question 2

What is the difference between primary and secondary bone neoplasia?

Answer 2

Primary- neoplasm of the tissue that makes structures of bone
Secondary- neoplasm that invades the bone or metastasises from another tissue

Question 3

Why is it difficult to distinguish Osteosarcoma from Osteomyelitis?

Answer 3

both are acute, both show soft tissue swelling and can have similar radiographic features such as bone destruction, lysis and proliferation

Question 4

Where does Osteosarcoma occur most commonly?

Answer 4

In the metaphysis

Question 4

Which group is more predisposed to Osteosarcomas?

Answer 4

larger, older breeds

Question 5

What are the clinical signs of Osteosarcoma? (4)

Answer 5

Present with a pathological fracture- fracture with very little impact
Crepitus- crunching sensation produced by motion
Palpably soft cortex
Local lymph node enlargement (but this can also be a sign of Osteomyelitis so be careful)

Question 6

What should we look for on a radiograph of a dog with suspected Osteosarcoma?

Answer 6

Osteolysis
Osteoproliferation & Periosteal reaction (formation of new bone)
Lack of trabecular bone pattern

Question 7

Most of the time signalment and radiography is enough to diagnose Osteosarcoma BUT if not, what other diagnostic tests can we perform? (2)

Answer 7

Fine needle aspirate of bone lesion
Biopsy- open or closed

Question 8

Osteosarcomas grossly metastasise in what percentage of cases?
Otherwise they micro metastasise in….

Answer 8

15% of cases grossly
90% micro metastasise

Question 9

In a patient with Osteosarcoma that hasn’t metastasised, how can we treat it and what is the prognosis? (2)

Answer 9

Amputation & Chemotherapy
Limb sparing surgery & Chemotherapy

[Survival of 1 year for both options]

Question 10

In a patient with a metastasised Osteosarcoma, how would we approach treatment and what is the prognosis? (3)

Answer 10

Palliative intent-
Analgesics with Bisphosphonate (mimics bone turnover)- survival is weeks-months
Palliative amputation- 4-6 months
Palliative radiation to 1+ sites with Bisphosphonate- 4-8 months

Question 11

Generally, what is the prognosis for Cats with Osteosarcomas?

Answer 11

Better than dogs- tends to be less aggressive with a lower metastatic rate

Question 12

What is the most common type of primary digital neoplasm?

Answer 12

Squamous cell carcinoma

Question 13

How do we treat digital neoplasms?

Answer 13

Amputation

Question 14

What is a Cat Lung digit?

Answer 14

type of secondary neoplasm- primary lung tumour metastasises and presents in one or more digits

Question 15

What is the prognosis of a Cat with a Lung digit tumour?

Answer 15

Poor- less than 2 months

Question 16

How do we differentiate a joint tumour to a bone tumour?

Answer 16

Joint tumours will cross the joint but bone tumours will not

Question 17

Briefly describe the pathogenesis of Osteomyelitis?

Answer 17

[Bones are normally resistant to infection] so Disruption to the normal balance of the bone > Inflammation & Ischaemia > Bone sequestrum > Focal osteoporosis > Periosteal reaction and new bone formation

Question 18

A post traumatic Osteomyelitis occurs after surgical implantations- how and why is this hard to treat medically?

Answer 18

the bacteria adhere to the biofilm of the implant- because of the slow turnover of bone in that area antibiotics tend not to work so need to remove implant to treat it

Question 19

What type of Osteomyelitis is associated with young animals?

Answer 19

Haematogenous

Question 20

How do we diagnose Osteomyelitis?

Answer 20

Radiographs and/or FNA

Question 21

How do we treat Osteomyelitis?

Answer 21

Antibiotics- culture and sensitivity based
Also can be local antibiotics with beads/ sponges
Treat for 6 weeks