L8- Osteosarcoma and osteomyelitis (copy)

Define osteomyelitis

commonly used term for infection of bone tissue- cortical bone and medullar cavity

Define neoplasia

Primary- Neoplastic process of the tissue that make the structure of the bone

Secondary- neoplasia that invades bone or metastasises from other tissue

Can also have neoplasia of muscle/tendon and joint capsule

How do you tell the difference between osteosarcoma vs osteomyelitis

• Can be difficult to distinguish

• Both can present acutely

• Both have soft tissue swelling

• Can have similar radiographic features

  • Osteomyelitis and neoplasia can cause destruction of areas of bone and bone may react with the formation of new bone

  • lysis and proliferation

what is the background for osteosarcomas

• Common

• Older, large breeds

• Metastatic ~15% gross pulmonary metastases

• at the time of diagnosis

• Occurs in the metaphysis

• If doesn’t fit consider other differentials -> osteomyelitis

what is the history for osteosarcoma

• Signalment- breed and age

• Lameness

  • Acute or chronic

  • Often v painful

  • Can present with a pathological fracture

• Recent wounds, trauma, other infection may point more towards osteomyelitis

What do you see on physical exam for osteosarcoma

• Refine the location with PE

• swelling in a common location (i.e. metaphysis)

• Bone pain

• ± crepitus

• ± palpably soft cortex

• Check local LN

• Full ortho exam

  • Carefully assess for pain in all long bones

• general exam

How do you work up osteosarcoma

• Radiograph the painful areas

  • osteolysis

  • Osteoproliferation

  • periosteal reaction

  • monostoic (one bone)

• Thoracic radiographs/ CT if suspicious of neoplasia to evaluate for metastases

What are some differential diagnoses for osteosarcoma

• Other- sarcoma (chondro-, fibro-, haemangio)

• Metastatic disease

• multiple myeloma

• Lymphoma

• Osteomyelitis

  • fungal or bacteria

• Bone cyst

How do you diagnose osteosarcomas in dogs

• FNA of bone lesion

  • 70% accuracy

  • Less technically challenging, less equipment, less risk fracture

• Biopsy

  • Jamshidi needle or michele trephine

  • open or closed

  • 80-90% accuracy

• Biochemistry (ALP), complete blood count, urinalysis

how do you stage osteosarcomas

• Gross metastatic disease in 15% of cases

• but micrometases in 90% of cases

• Imaging

• Local staging

What are the principles for treating osteosarcoma

• The primary tumour has significant impact on QOL rn

• Metastatic disease affects patients survival time

• Often unremittingly painful if left alone

  • analgesia alone won’t do

• must treat primary successfully

• must consider secondary spread

  • 90% have micro mets in lungs at time of diagnosis

• must build client communication into treatment time

What are some methods of treating osteosarcoma

• Amputation (4 months)

  • Complete resection to prevent further mets/local disease control

  • removes pain

  • need carefully assess for other ortho/neuro dx

• amputation and chemotherapy (-1yr)

• Limb sparing and chemotherapy (-1 year)

• Radiotherapy (pallative)

• NSAIDS ± bisphosphates (palliative)

• Euthanasia

How do you evaluate suitability for amputation of limb due to osteosarcoma

• BCS

• Concurrent orthopaedic disease

Partial amputation for:

• stump sock prosthesis

• Intraosseous endoprothesis (ITAP)

How do you perform limb sparing surgery for treating osteosarcoma

• Remove disease portion of bone whilst preserving limb

• contraindicated if pathological fracture due to spread to local tissue

• associate with good QOL and MST

How common are digital masses

• common

• >12% all sublingual (nailbed) masses =neoplasia

• 60% digital masses are neoplasia

• The most common tumour types are SCC

  • 50% of malignant digital tumours > malignant melanoma > STS > MCT> OSA

How do digital neoplasms present

• Lameness

• Mass lesion

• Ulceration

How do you diagnose digital neoplasms

• Radiographs

• Staging

• sampling

what is the treatment/outcome of primary digital neoplasm

• Amputation

• Prognosis depends on tumour type and tissue of origin

what are the digital masses/neoplasms in cats

• 70% digital masses are malignant

• SCC > FSA> ADC > OSA> HSA

what is cat lung digit

• Metastasis of primary pulmonary mass to digit

• present for lameness

• poor prognosis ~2 months

What is a chondrosarcoma

• 2nd most common primary bone tumour but overall rare

• diagnostic investigations as for osteosarcoma

• Much lower metastatic rate and longer survival time

What is the background and presentation of joint tumours

• Background- sarcomas

• Presentation

  • Lameness

  • ± joint swelling

  • large breed, older dogs

how do you diagnose joint tumours

• Cytology: FNA/synovial fluid

• Imaging including staging

• Joint tumour will cross the joint!

  • bone tumours will not

• biopsy +IHC

What is the treatment/outcome of joint tumours

• Depending on type and stage

• usually amputation

What are some muscular neoplasms

• rhabdomyosarcoma

  • Rare

  • Think more like STS

• Haemangiosarcoma

  • Intramuscular vs subcut

What are some adipose tumours

• Benign lipoma

  • intramuscular lipoma

• Infiltrative lipoma

• liposarcoma

What are infiltrative lipomas

• Radical excision

• recurrence

What are liposarcomas

• Consider like STS

• However FNA may lead to misdiagnosis

What is the background pathogenesis for osteomyelitis

• Bone resistant to infection, some disruption to normal balance

• Inflammation chance local cytokines – ischaemia

• +/- Sequestrum

• Adjacent to ischaemia focal osteoporosis

• Periosteal reaction results in new bone

What are some post traumatic causes of osteomyelitis

• Implants specific consideration

• biofilm

• nosocomical origin MDR

What is the pathogenesis for haematogenous causes of osteomyelitis

• Young animals

• Rare

• microtrauma?

What is the acute presentation of osteomyelitis

• Injury or surgery

• systemic signs

  • pyrexia, leukocytosis

• lameness, acute onset high grade

• Swelling/pain palpation

• ± draining sinus

What is the chronic presentation of osteomyelitis

• Historic injury/surgery

• Low/moderate grade lameness, intermittent

• sinus often

• pain palpation

• potential pathological fracture

How do you diagnose osteomyelitis

• Radiographs

• FNA

• Biopsy

• C+S

How do you treat osteomyelitis

• Prompt

• antibiotics

  • Initially empirical an then based on C&S

  • Consider local antibiotics

    • beads/sponges

  • long course typical~6 weeks

• Remove structures that protect bacteria or maintain biofilm

  • implants and sequestra

• monitoring

• prognosis variable but guarded

How do you prevent osteomyelitis

• Surgical technique and asepsis

• Appropriate perioperative protocols