Osteosarcoma & Osteomyelitis Flashcards
What is Osteomyelitis?
infection in the bone tissue- cortical bone and medullary cavity
What is the difference between primary and secondary bone neoplasia?
Primary- neoplasm of the tissue that makes structures of bone
Secondary- neoplasm that invades the bone or metastasises from another tissue
Why is it difficult to distinguish Osteosarcoma from Osteomyelitis?
both are acute, both show soft tissue swelling and can have similar radiographic features such as bone destruction, lysis and proliferation
Where does Osteosarcoma occur most commonly?
In the metaphysis
Which group is more predisposed to Osteosarcomas?
larger, older breeds
What are the clinical signs of Osteosarcoma? (4)
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)
What should we look for on a radiograph of a dog with suspected Osteosarcoma?
Osteolysis
Osteoproliferation & Periosteal reaction (formation of new bone)
Lack of trabecular bone pattern
Most of the time signalment and radiography is enough to diagnose Osteosarcoma BUT if not, what other diagnostic tests can we perform? (2)
Fine needle aspirate of bone lesion
Biopsy- open or closed
Osteosarcomas grossly metastasise in what percentage of cases?
Otherwise they micro metastasise in….
15% of cases grossly
90% micro metastasise
In a patient with Osteosarcoma that hasn’t metastasised, how can we treat it and what is the prognosis? (2)
Amputation & Chemotherapy
Limb sparing surgery & Chemotherapy
[Survival of 1 year for both options]
In a patient with a metastasised Osteosarcoma, how would we approach treatment and what is the prognosis? (3)
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
Generally, what is the prognosis for Cats with Osteosarcomas?
Better than dogs- tends to be less aggressive with a lower metastatic rate
What is the most common type of primary digital neoplasm?
Squamous cell carcinoma
How do we treat digital neoplasms?
Amputation
What is a Cat Lung digit?
type of secondary neoplasm- primary lung tumour metastasises and presents in one or more digits
What is the prognosis of a Cat with a Lung digit tumour?
Poor- less than 2 months
How do we differentiate a joint tumour to a bone tumour?
Joint tumours will cross the joint but bone tumours will not
Briefly describe the pathogenesis of Osteomyelitis?
[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
A post traumatic Osteomyelitis occurs after surgical implantations- how and why is this hard to treat medically?
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
What type of Osteomyelitis is associated with young animals?
Haematogenous
How do we diagnose Osteomyelitis?
Radiographs and/or FNA
How do we treat Osteomyelitis?
Antibiotics- culture and sensitivity based
Also can be local antibiotics with beads/ sponges
Treat for 6 weeks
