Pathology Flashcards
What is the most common degenerative joint disease?
Osteoarthritis
What is the pathogenesis of osteoarthritis?
Chronic progressive destruction of articular cartilage
- can be 1° or 2° (eg. trauma, congenital abnormality, avascular necrosis, other joint disease)
How does osteoarthritis present?
1) Pain
2) Limitation of movements
3) Swelling and osteophytes
4) Cervical spondylosis spinal nerve compression
What are the 3 forms of osteoarthritis?
1) Primary generalised OA
- most common in post-menopausal women
2) Erosive inflammatory OA
- severe destructive disease w rapid progression
3) Hypertrophic OA
- florid osteophyte formation, bone sclerosis w slow progression
What is the pathogenesis of hypertrophic osteoarthritis?
Multifactoral
eg. ↑joint load
degradation of articular cartilage
biochemical abnormalities (eg. ↓proteoglycans, protein synthesis, chondrocyte replication)
Genetic abnormalities (familial mutation of type 2 collage COL2A1)
Degenerative, inflammatory and reparative activity involving articular cartilage & subarticular bone, with secondary effects on synovium, muscle and nerves.
What is the characteristic histological findings in osteoarthritis?
Damage and destruction of articular cartilage:
- thinning
- erosion
- fibrillation/erosion → “cracking”
What are 2 bone presentations of osteoarthritis?
1) Eburnation
- exposed bone w polished surface due to contact friction of bone surface
2) Formation of subchondral cyst
3) Thickening of subarticular bone
What are 4 radiological features of osteoarthritis?
1) Narrowing of the joint space
2) Sclerosis (thickening of subchondral bone)
3) Subchondral cyst
4) Osteophytes (peripheral growths of bone and cartilage)
What are 5 pathological findings of osteoarthritis?
1) Destruction of articular cartilage
2) Eburnation and thickening of subarticular bone
3) Formation of subchondral cyst
4) Formation of osteophytes/bone (eg. Herberden’s nodes)
5) Reactive thickening of synovium
6) Secondary changes to surrounding tissue (eg. muscle atrophy)
What is the normal structure of an intervertebral disc?
1) Central nucleus pulposus (water, proteoglycans)
2) Surrounding annulus of obliquely oriented collagen fibres
3) Cartilaginous end plate
What are 4 possible aetiologies/components of intervertebral disc degeneration?
1) Genetics
2) Age-related “wear and tear”
- eg. nucleus pulposus becomes dehydrated, fibrotic and atrophied
3) Mechanical
- eg. occupational, bad posture, strain, trauma → crack/tears in disc annulus and nucleus pulposus
4) Others
- eg. nutrition, metabolic, infection
Bulging/prolapse of nucleus pulposus through a weakened annulus is most common in which direction?
Posterior/posterolateral
- with the outer layers of the annulus still intact
What is a disc herniation?
Nucleus pulposus of intervertebral disc spurts out through a tear in the annulus into either spinal canal or foramen.
What is the difference between a disc prolapse, extrusion and sequestration?
Bulging: outer layers of annulus intact
Extrusion: tear in annulus but nucleus pulposus intact
Sequestration: tear in annulus + portions of nucleus breaks free
What are 2 complications of disc bulging/herniation?
1) Posterior → spinal cord (myelopathy)
- cervical myelopathy
- spasticity
- unsteady gait
- clumsiness in hands
2) Postero-laterally → nerves roots (radiculopathy)
- dermatomal neurological deficits (motor or sensory)
What is rheumatoid arthritis?
Systemic chronic inflammatory autoimmune disease affecting many tissues but principally attacking the joints
Rheumatoid arthritis EPC:
Most common in (M/F)
Age: _____________
Rheumatoid arthritis EPC:
Most common in F
Age: 40-60y
Which part of the body is most common affected by RA, and where are the typical extra-articular areas of involvement?
Articular:
1) PIP and MCP of hand
2) Wrist
3) Elbows
4) Knees
Extra-articular:
1) Skin
2) Heart
3) Blood vessels
4) Muscles
5) Lungs
What are 2 key autoAbs used in the diagnosis of RA?
1) Rheumatoid factor (RF)
2) Anti-citrullinated protein Ab (ACPA)
What is the main genetic predisposition for RA?
HLA-DR4 (MHC Class 2)
Describe the pathogenesis of RA.
Cytokine-mediated CD4+ T cell inflammation
1) Susceptibility
a) genes (eg. HLA) → loss of self-tolerance and lymphocyte regulation
b) environmental (eg. infection, smoking) → enzymatic modification of self proteins
2) CD4+ T cell activation
a) Th1 → M1 macrophage
b) Th17 → cytokines
3) Cell responses:
a) B cell → RF → immune complex deposition → joint injury
b) Cytokines + M1 → joint cell proliferation + enzymes and PGE2
c) Endothelial activation → expression of adhesion molecules → accumulation of inflammatory cells
4) Pannus formation
- destruction of bones, cartilage, fibrosis, ankylosis
What are the 4 pathological features of RA?
1) Synovial inflammation
- chronic inflammatory infiltrate, lymphoid aggregates, exudate, fibrin → swelling and villous formation of the synovium
2) Pannus formation
- granulation tissue → fibrosis → ankylosis
3) Destruction of adjacent bone → joint deformity
4) Formation of rheumatoid nodules
What is the characteristic histological feature of systemic rheumatoid arthritis?
Rheumatoid nodules
- granuloma w central zone of fibrinoid necrosis
- found in many organs
What are 3 systemic effects of rheumatoid arthritis?
1) Rheumatoid nodules
2) Necrotising vasculitis
3) Amyloidosis
What are 2 causes of autoimmune arthritis?
1) SLE
2) Rheumatic fever
3) Systemic sclerosis
What are 4 characteristics of seronegative spondyloarthropathies?
1) Sero-negative (lack of rheumatoid factor)
2) High incidence of HLA B27 Ag
3) Axial location (eg. vertebral/sacro-iliac joint) or asymmetric involvement of peripheral joints in the digits
4) Pathology often in ligamentous attachments rather than synovium
What are 3 forms of seronegative spondyloarthropathies?
1) Ankylosing spondylitis
2) Psoriatic arthropathy
3) Reactive arthrtitis