Histopathology 15: Bone Pathology Flashcards
What part of long bones encompasses the growth plates ?
Metaphysis
What are some of the main differences between cancellous and cortical bone ?
Cortical
- Occurs in the long bones
- 80% of skeleton
- Appendicular component
- 80-90% calcified
- Mainly mechanical and protective
Cancellous
- Found in the vertebrae and pelvis
- 20% of skeleton
- Axial component
- 15-25% calcified
- Mainly metabolic function
- Large surface
How do osteoblasts inhibit osteoclast formation ?
- Osteoblasts release osteoprotegrin (OPG)
- which inhibits RANKL from binding to the RANKL receptor on osteoclast precursors
- This blocks differentiation into mature osteoclasts.
List fractures commonly seen in patients with osteoporosis ? (4)
- Colle’s fracture of the wrist
- neck of femure and intertrochanteric fractures of the hip
- Pelvic
- Vertebra
What are the biochemistry findings in a patient with osteoporosis ?
What is best Ix?
Normal calcium, phosphate, ALP
Ix: Bone Densitometry
- -1 to -2.5 = osteopaenia
- < - 2.5= osteoporosis
What are the histological findings in osteoporosis ?
Loss of cancellous bone
List 2 ty typical X-ray findings suggestive of Osteomalacia ?
Bowing of the legs in Rickets
Horizontal pseudofractures in looser’s zones
List signs and symptoms of Rickets in children ?
Bone pain
Bowing tibia
Rachitic rosary
frontal bossing
Pigeon chest
Delayed walking
What is a histological feature of Osteomalacia ?
reduced mineralised bone relative to the osteoid (less mineralisation)
List symptoms of hyperparathyroidism?
Basically Sx of hypercalcaemia:
- Moans - depression, confusion
- Stones- calcium oxalate renal calculi
- Bones- bone pain
- Groans- constipation, pancreatitis, polyuria
Which metabolic bone disease shows histological bone changes of osteitis fibrosa cystica ?
Hyperparathyroidism
List 3 x-ray findings suggestive of hyperparathyroidism ?
- Brown’s tumours (osteitis fibrosa cystica)
- Salt and pepper skull
- Subperiosteal bone resorption in phalanges
What is renal osteodystrophy ?
A term that describes all skeletal changes associated with chronic renal disease
- Increased bone resorption (osteitis fibrosa cystica)
- Osteomalacia
- Osteosclerosis
- Growth retardation
- Osteoporosis
What is the most common causative organism for osteomyelitis in adults ?
S.Aureus
List 2 histological findings in Paget’s disease ?
Huge Osteoclasts with >100 nuclei
Mosaic/jigsaw pattern of lamellar bone (due to line between areas of new bone formation)
List the x-ray features of osteoarthritis ?
L- loss of joint space
O- osteophytes
S- subchondral sclerosis
S- subchondral cysts
List 2 features of osteoarthritis in the hands ?
Heberden’s nodes (DIP joints)
Bouchard’s nodes (PIP joints)
List 6 features of rheumatoid arthritis in the hands and wrist?
Sparring of the DIP joints
Radial deviation of the wrist
Ulnar deviation of the fingers
Swan neck deformity of the fingers
Boutonniere’s deformity of the fingers
“Z” shaped thumb
Joint spared in rheumatoid arthritis
DIP (distal interphalangeal joint)
List 3 histological features of rheumatoid arthritis ?
Proliferative synovitis
Pannus formation
Grimley sokoloff cells- multinucleate giant cells
Which infectious organism causes osteomyelitis with Langerhans-type giant cells on histology ?
Tuberculosis
Name of lesion in gout (pathogenic)
Tophus
Which shape Chrystal are seen in gout and pseudogout?
Gout = needle shaped Pseudogout = rhomboid shaped
Which syndrome has the following features: Blue sclera, hearing loss, miss shaped teeth and recurrent fractures ?
Oesteogenesis imperfecta (autosomal dominant)
Describe the 4 stages of fracture repair ?
- Organisation of haematoma
- fibrocartilaginous callus formation
- Mineralisation of fibrocartilaginous callus
- remodelling of bone along weight bearing lines
Brown cell tumours are a histological feature of which condition?
hyperparathyroidism
Main joint in gout
Main joint in pseudogout
Great toe
Knee
Type of cell seen on histology in Ewing’s sarcoma
small round blue cells
Also see onion-skinning of the periosteum
Most common primary bone sarcoma and where it mainly occurs
Key feature on X-ray
Osteosarcoma - knee
Codman’s triangle
5 tumours that metastasise to bone in children
- neuroblastoma
- Wilm’s tumour
- osteosarcoma
- Ewing’s sarcoma
- Rhabdomyosarcoma
2 main bones affected in Paget’s disease
Lumbar spine
Skull
Which mechanism regulates osteoclast formation and function
Paracrine molecular mechanisms
Name for reduced bone mass
Osteopaenia
How to study Bone mineralisation
Using osteoid parameters
Drug that increases R of osteoporosis
Steroids
Affect ALL THREE types of cell (Osteoclasts, -blasts and -cytes)
Main Primary cause of hyperpPTH
3 causes of secondary
- Parathyroid adenoma (85-90%)
- Chronic renal insufficiency
- Vitamin D deficiency
- Malabsorption
Main bones affected in osteomyelitis (4)
- Vertebrae
- Jaw (secondary to dental abscesses)
- Toe (secondary to diabetic skin ulcers or vascular ulcers, > 3mm)
- Long bones (usually metaphysis)
Where can you get an abscess in TB?
Psoas
X-ray changes in osteomyelitis
- Usually appear 10 days after the onset of osteomyelitis
- Mottled rarefaction and lifting of periosteum
- > 1 week: irregular sub-periosteal new bone formation is seen which is called involucrum (layer of new bone that forms around dead bone)
- Later: irregular lytic destruction (takes 10-14 days)
- Some areas of the necrotic cortex may become detached. This is called sequestra (takes 3-6 weeks)
Organism in syphilis
Treponema pallidum
NB a rare cause of osteomyelitis
Organism causing lyme disease
Borrelia burgdorferi
Late presentation of Lyme disease
arthritis
NB earlier presentation = the classic rash that looks like target sign (erythema migricans)
Aetiology of osteoarthritis
- degenerative joint disease - mainly age-related
- synovium becomes very chronically inflamed with infiltration of inflammatory cells
HLA associated with rheumatoid arthritis
HLA-DR4 and DR1
Histology of rheumatoid arthritis
- Proliferative synovitis (Thickening of synovial membrane)
- Pannus formation with exuberant inflamed synovium
- Grimley-Sokoloff cells
