Path 2017 exam

Question 1

1. Briefly outline the pathological events occurring during acute disc herniation. (10 marks)

Answer 1

Trauma to IVDs, commonly due to:

• Jarring (especially Cx spine)
• Combined F/E with spine under load (especially LS spine)
• Sudden straining whilst in unstable position (especially LS spine)

Mechanism:
Major force
- eg car accident, fall from height
- Complete disc rupture (likely) Repeated microtrauma
- eg recreational or occupational overuse
- Partial disc herniation (likely)

Degrees of herniation:
Complete disc herniation
- Outer layers of annulus fibrosis breached
- May get rupture of PLL
- Nuclear material may break loose and lie free in:
o Spinal canal (may cause canal stenosis)
o IVF (may cause foraminal stenosis) Partial disc herniation
- Outer layers of annulus fibrosis remain intact
- Increased nuclear pressure → protrusion of nuclear material into tears → bulging of disc (to one side of PLL)
- Gradual onset of symptoms (back pain because annulus fibrosis has nerve supply)
- May progress to complete rupture

Direction of herniation
Central disc herniation
- Spinal canal stenosis (spinal cord compression), causing UMN Ssx
- Compression of Cauda Equina (LMN Ssx) Posterolateral disc herniation
- IVF stenosis (compression of exiting spinal nerve or rootlet), causing LMN Ssx
Posterior disc herniation

May also get joint displacement/spondylolisthesis

Question 2

Briefly outline the pathological events occurring during chronic disc degeneration (10 marks)

Answer 2

1. Normal ageing (biochemical changes)
   - After around age 30, biochemical changes to the nucleus pulposis:
   ➢ ↓ proteoglycan size + synthesis
   ➢ ↓ H2O and elastin content
   ➢ á collagen content
   - Nucleus pulposis becomes soft, brown, dessicated structure, less able to resist mechanical forces
2. Biomechanical changes
   o Decreased hydrostatic pressure
   o Decreased nucleus pulposis elasticity
   o Decreased disc height and flattening of IVD
3. Degenerative changes
   - Decreased ability to resist shear forces → development of fissures in annulus fibrosis → herniation of nuclear material:
   o Into nervous system → causes IVF or spjnal canal stenosis
   o Into vertebral endplates → Development of Schmorl’s nodes
   - Increased forces on vertebral endplates may also lead to microfractures
   - Reactive bone formation:
   o Around Schmorl’s nodes and other sites of herniation
   o Spondylosis (flattening of IVD and osteophyte formation) → In later stages, osteophytes may impinge on spinal cord or exiting nerve roots (UMN or LMN Ssx)
   - Displacement of facet joints
   - Fibrocartilage replaces gelationous nucleus pulposis
   - Segmental fibrosis occurs → stabilization of disc lesion and decreased back pain

Question 3

Discuss stages of pathology in Ankylosing Spondylitis (AS) (6 marks)

Answer 3

1. Inflammation – Infiltration by inflammatory cells leads to granulation tissue development, which commonly affects:
   - Entheses (bony attachments for tendons and ligaments):
   o Common sites: Vertebrae and pelvis
   o Destruction of: Bone and fibrocartilage
   - Synovium:
   o Common sites: Facets, CV joints, SIJs
   o Destruction of: Subchondral bone, articular cartilage
2. Fibrosis/repair
   - Inflammation subsides and granulation tissue replaced by fibrous scar tissue
   - Fibrosis of joint capsule
3. Ossification and ankylosis – Reactive new bone formation in:
   - Reactive new bone formation in:
   o Articular bone (results in sclerosis)
   o Adjacent ligaments & other joint structures
   o Ossification of fibrous tissue of joints → ankylosis
4. Remission
   - Recession of pathological processes
   - 50% of people will not have another exacerbation

Question 4

List 5 radiological manifestation in ankylosing spondylitis (5 marks)

Answer 4

SIJ
Early:
- “Rosary beads” (articular erosions)
- “Pseudowidening” (Loss of articular cortex definition)
- Subchondral osteoporosis with patchy reactive sclerosis
- Diminished joint space
Late:
- “Ghost” joint margin – Visualisation of articular cortex through ankylosed joint
- “Star sign” – Ossification of superior sacroiliac ligaments (triangular opacity at superior SIJ) -

SPINE
“Romanus lesion” – Lucent VB corner erosion due to inflammatory destruction
- “Squared” or “barrel-shaped” vertebrae
- Marginal syndesmophytes (ossification of annulus fibrosis) → “bamboo spine” (multiple ankylosed IVDs/vertebrae
- “Trolley track” appearance – Due to fusion of facet joints
- “Dagger sign” – Due to calcification of supraspinous ligaments causing SP ankylosis
- “Ballooning” of IVDs - Due to osteopenic vertebral endplates that become concave due to excessive pressure
- Schmorl’s nodes

Question 5

Name the 5 clinical variants of psoriatic arthritis (PsA); and describe the number and type of joint typically affected in each variant

Answer 5

Peripheral (DIP dominant)

• 5-10%
• Men
• DIPs affected
• Oligo/polyarthtiris
• Asymmetric
• Nail changes

Peripheral symmetric seronegative polyarthritis

• 25-50%
• Females
• Similar to RA
• Polyarthritis (>5 joints)
• Small hand/feet joints: PIPs & MCPs
• Large joints: Knee, hip, ankle, wrist
• Psoriasis often severe

Asymmetric oligo/pauciartucular arthritis

• 35%
• Similar to OA (mild)
• Mono/oligoarthritis (1-3 small and large joints)
• Small joints: DIPs, PIPs & MCPs
• Large joints: Hip, knee
• Dactylitis

*To remember large joints for symmetric/asymmetric = ALSU (Asymmetric lower; symmetric upper [extremity joints]), both have wrist & ankle

Axial arthritis (spondylitis & sacroiliitis)

• 5-20%
• Male
• Oligo/polyarthritis
• Asymmetric
• Commonly: Cx, Lx, SIJs
• Also: Peripheral joints (hands, arms, legs, feet)

Arthritis Mutilans
- <5%
- Severe, destructive, erosive
- Polyarthritis
- Commonly: DIPs, small joints of hands &amp; feet
Also: Neck, lower back

Question 6

Describe the typical SLE patient (3 marks)

Answer 6

• Female (90%), 20-40 years old (but may occur at any age)
• Australia: Increased frequency in Aboriginals and people of South-East Asian origin
• Potential history of CNS manifestations (cognitive dysfunction, HA, seizures, psychosis); GIT involvement (bleeding and diarrhea); and/or fever, fatigue, weight loss
• May have some type of skin rash: Malar rash (40% presenting Sx) or photosensitivity rash (29% presenting Sx)

Question 7

Discuss mechanism of tissue damage in SLE (6 marks)

Answer 7

1. Genetically predisposed individual (MHC class 2)
2. Environmental trigger (eg drugs, viruses)
3. Helper T-cells become reactive to self-peptides, causing:
4. Activation of B-cells → differentiate into plasma cells
5. Plasma cells produce IgG autoAb’s (especially ANAs), will result in two things:

AutoAb mediated direct damage (Ssx dependent on specific mix of AutoAb’s present and tissues affected)

Immune complex deposition:

6. Ag-Ab complexes form and deposit into various body tissues
7. Complement release, causing:
   - Small vessel vasculitis → thrombosis, ischaemia and tissue necrosis
   - Polyarthritis/arthralgia – Distal joints affected more (fingers, wrists, knees and toes)

TISSUES AFFECTED:

• Lymphoid system (lymphadenopathy, splenomegaly)
• Skin inflammation
• Heart involvement (endocarditis, myocarditis, pericarditis)
• CNS
• Renal/kidneys
• Vasculitis
• Arthritis

Question 8

List commonest early presenting symptoms in SLE (4 marks)

Answer 8

• Arthritis (69%)
• Malar rash (40%)
• Low-grade fever (36%)
• Photosensitivity rash (29%)

Question 9

List the commonest overall symptoms which are seen in SLE in the course of time (4 marks)

Answer 9

• Haematologic (100%)
• Arthritis (90%)
• Skin (85%)
• Fever (83%

Question 10

Briefly compare the epidemiology and aetiology of the two forms of Reiter’s syndrome (6 marks)

Answer 10

SEXUALLY TRANSMITTED
Epidemiology:
- Post-venereal infection ratio is 5-10M:1F
- Mainly males 20-40yo
- ~1-3% of all people with nonspecific urethritis develop an episode of arthritis
Aetiology:
- Usually chlamydia trachomatis

DYSENTERIC
Epidemiology:
- Post-enteric infection ratio is 1M:1F
- Usually seen in women, children and elderly
- ~1-4% of all people will develop an episode of arthritis after an enteric infection
- 20-25% of HLA-B27 positive individuals will develop arthtirits after bacterial enteritis
Aetiology:
- Shigella
- Salmonella
- Yersinia
- Campylobacter

Question 11

Define the term Reactive Arthritis (2 marks)

Answer 11

Syndromes characterized by sterile inflammation of joints from infections at non-articular sites (eg dysenteric or sexually transmitted infections) that are classified as a seronegative spondyloarthropathy and is associated with non-bacterial urethritis/cervicitis, conjunctivitis and mucocutaenous lesions

Question 12

Describe the pathological process occurring in the skin in dermatomyositis (6 marks)

Answer 12

1. Trigger (viral infection)
2. Autoimmune reaction (T-lymphocytes activated → B-cells differentiate into plasma cells → Release autoAb’s)
3. Deposition of immune complexes into basal membrane of skin, and small blood vessels supplying skin
4. Release of complement, causing vasculitis
5. Vascular dilation and lymphocytic infiltration of dermis
6. Basal cell liquefaction, leading to epidermal atrophy

Question 13

Describe skin signs in dermatomyositis (6 marks)

Answer 13

• Dusky, erythematous rash – Often the first manifestation. A slightly raised, patchy bluish-purple rash that may be smooth or scaly and can be present on: forehead, chest and back, elbows and knees, forearms and lower legs, medial malleoli and radiodorsal surface of PIPs and MCPs
• Gottron’s papules – Pathognomonic for DM. Slighlt elevated, violaceous papules/plaques that occur over bony prominences (eg elbows, knees and finger joints)
• Heliotrope rash – A purple rash that occurs periorbitally (on and around eyes/eyelids).

Question 14

Compare gout and pseudogout 10 marks)

Answer 14

Can compare based on:
- Aetiology (hyperuricaemia vs chondrocalcinosis)

• Type & appearance of crystal (sodium urate; negatively birefriengent needle-shaped VS calcium pyrophosphate; positively birefringent & polygonal)
• Pathophys stages (1. Asymptomatic hyperuricaemia 2. Acute gouty 3. Intercritical 4. Chronic tophaceous VS 1. Asymptomatic chondrocalcinosis 2. Acute pyrophosphate synovitis 3. Chronic pyrophosphate arthritis)
• Typical pt: (Men >30; diet high in purine & excess alcohol; HTN & obese VS elderly people)
• Joints (small VS large)
• Pain (severe VS mod)
• Swelling (severe VS mod)
• Crystal Ssx (tophi VS no lumps/crystals)
• Complications (renal calculi and insufficiency VS None)
• Lab tests (High uric acid VS serum calcium)
• Radiology (Tophi & joint erosion VS cartilage calcification & changes similar to OA)

Question 15

Discuss the events occurring in joints and tendons as RA progresses through from early to advanced stages (10 marks)

Answer 15

Stage 1: Synovitis
- Early changes:
o Vascular congestion → vasodilation
o Proliferation of synoviocytes → synovial thickening
o Infiltration of articular cartilage and subchondral bone by polymorphs, lymphocytes and plasma cells
- Gradual thickening and villous formation of the synovium
- Effusion into joint and tendon sheaths

Stage 2: Destruction
- Persistent inflammation → Joint and tendon destruction
- Articular cartilage erosion, due to:
o Pannus (granulation tissue) formation and spread
o Action of proteolytic enzymes
o Vascular tissue in folds of synovial reflections (neoangiogenesis)
- Bone erosion, due to:
o Invasion of granulation tissue
o Osteoclastic resorption
- Tendon sheath destruction, due to:
o Tenosynovitis
o Invasion of collagen bundles by granulation tissue and inflammatory elements → eventual tendon rupture

Stage 3: Deformity
- Inflammation often subsides by end of this stage
- All of the following cause progressive joint instability and deformity; and structural/mechanical issues cause patient’s pain:
o Articular destruction
o Capsular stretching
o Tendon rupture
- Typical deformities:
o Fingers: Swan neck & Boutonniere’s (destruction of flexor/extensor tendons and sheaths), Bouchard’s (PIPs) & Hagarth’s (MCPs) nodes, ulnar deviation
o Wrist: Radial and palmar deviation
o Knees and ankles: Valgus deformities
o Toes: Claw & hammer toe