Basic Science - Pathology Flashcards
What is the commonest benign bone tumour?
Osteochondroma
What is an osteochondroma and what is the treatment of a growing or painful lesion?
Bony outgrowth externally with cartilagenous cap
Excisional biopsy
What is the cause of multiple osteochondroma?
Autosomal dominant hereditary disorder
Where do enchondroma occur?
Within - intramedullary and at metaphysis
Anatomically - Femur, humerus, tibia and small bones of hand and feet
What are the consequences of an enchondroma?
Can weaken bone and result in pathologic fracture
What is the treatment for a enchondroma if there has been a fracture or risk of one?
Curretage and bone graft
What is a simple bone cyst?
Single fluid filled cyst in bone = Growth defect from the physis, therefore metaphyseal in long bones
What is an aneurysmal bone cyst?
Multiple chambered filled with blood = arteriovenous malformation. Lesion locally agressive and causes cortical destruction and pain
Where do aneurysmal bone cysts occur?
Metaphyses of long bones, flat bones and vertebral bodies
What is a giant cell tumour of the bone?
‘Soap bubble’ X ray appearance, locally aggressive/ destructive tumours of multi nucleated giant cells arising in metaphyseal region normally. Can also involve epiphysis ans subchondral bone
What is the treatment of a GCT of bone?
Intralesional excision with phenol, bone cement or liquid nitrogen used to reduce recurrence
Cortical destruction can = joint replacement
What is a complication of GCT?
Metastases to lung causing benign pulmonary GCT
What is fibrous dysplasia?
Lesions of fibrous tissue and immature bone caused by genetic mutation.
In adolescence
Can cause defective mineralisation = angular deformities. Bone is also wider with thinner cortices
What is the consequences of fibrous dysplasia?
Shepherds crook deformity of proximal femur if involved
Stress fracture
Treatment of fibrous dysplasia?
Bisphosphonates for pain
Internal fixation stabilising and cortical bone graft for pathological fracture
What is osteoid osteoma?
A site of immature bone surrounded by intense sclerotic halo
Adolescence
Occurring at proximal femur, diaphysis of long bones and vertebrae
Causes intense pain, worse at night due to inflammation
Treatment of osteoid osteoma?
NSAIDS for pain
Some require CT guided radioablation or en bloc excision
What is a Brodies abscess?
Lytic bone lesion caused by subacute osteomyelitis
What is a Brown tumour?
Lytic bone lesion caused by hyperparathyroidism
What is the cause of enchondroma?
Failure of normal enchondral ossification
What are the RED FLAGS of any metastatic bone tumour?
Constant pain, ?severe and worse at night
Systemic - weigh loss, fatigue and loss of appetite
Be aware of older and younger patients
What is the investigation done initially if suspicious of bone malignancy ?
X Ray
In whom are primary bone tumours likely to occur?
Under 25’s
What feature would mandate urgent referral ?
Substantial, ill defined bony swelling
What would a primary bone tumour show on X ray?
Cortical destruction, periosteal reaction, new bone formation combined with lysis from destruction and extension into surrounding tissue
What is the commonest primary bone cancer?
Osteosarcoma
Site of osteosarcoma?
60% involve bones around knee
Other sites = proximal femur and humerus + pelvis
What is the method of spread of osteosarcoma?
Haematogenous + lymphatic in some cases
What adjuvant treatment can be used for osteosarcoma?
Chemotherapy, NOT radiotherapy
Where will patients with osteosarcoma often have mets?
Pulmonary
What is Ewings Sarcoma?
Malignant tumour of primative cells in marrow
Is radio and chemo sensitive
What can be a presentation of Ewings sarcoma?
Much like osteomyelitis
Fever, raised inflammatory markers and warm swelling
What is the definitive treatment of primary bone cancer?
Surgery for removal - margin of 3-4 cm + cuff of muscle
Staging through CT and MRI and biopsy
Often limb salvage afterwards involving joint reconstruction with large replacements to counteract bone loss
What cancers will tend to metastasise to bone?
Breast, prostate, lung, renal cell and thyroid adenocarcinoma
Features of breast cancer bone mets?
Can be lytic ( black on x ray) or sclerotic/ blastic ( white on X ray)
Feature of prostate cancer bone mets?
Sclerotic lesions
Radiotherapy and hormone treatment can reduce fracture risk
Osteoblastic activity means fractures more likely to heal
Features of lung cancer bone mets?
Lytic lesions
Features of renal cell carcinoma bone mets?
Large, very vascular lytic lesions
Single bone met + resectable primary tumour can = cure by surgery
How can a primary bone tumour be excluded if lesion found on X ray?
By bone scan or ?MRI
What would indicate impending pathological fracture and therefore intervention?
Pain on weight bearing especially
Over 50% bone diameter
Cortical thinning
At risk area
What is skeletal stabilisation?
Insertion of long rods/ intramedullary nails or joint replacement if destruction of joint
Any surgery = HIGH risk DVT so prophylaxis must be taken
How can spinal cord compression be treated?
Usually in advanced spinal mets
By radiotherapy or anterior or posterior surgical decompression
What is a ganglion cyst?
Cyst around synovial joint or the synovial tendon sheath caused by herniation of weak portion of joint capsule
What are types of ganglion cyst?
Developmental - i.e. juvenile Bakers’s cyst
Resulting from joint damage or arthritis - i.e. Adult Baker’s cyst, mucous cyst of DIP joint, wrist ganglion
What are the features of a ganglion cyst?
Well defined, quite firm and transilluminate
What is a bursitis?
Inflamed bursae occurring due to repeated pressure and trauma. Can also be caused by gout and a bursal abscess can be caused by bacterial infection.
Thickened bursal sack can be left after inflammation subsides
What sites are prone to avascular necrosis (AVN)?
Femoral head Femoral chondyles Head of humerus Capitellum Proximal pole of scaphoid Proximal part of talus
Causes of AVN
Fracture Alcoholism and steroid use or abuse Primary hyperlipidaemia Thrombophilia Sickle cell disease Antiphospholipid in SLE Caisson's disease
How does lipid accumulation cause AVN
Increased fat in circulation = increased marrow fat content compressing venous outflow from bone
What is sequelae of AVN?
Necrosis Patchy sclerosis Subchondral collapse Irregularity of articular surface Secondary osteoarthritis
Treatment of osteoarthritis?
If no articular collapse in an amenable site - drilling under fluroscopy to decompress bone
Articular collapse = joint replacement
Fusion? in wrist or ankle and foot
