LOCO6 Flashcards
Explain the pathophysiology of heterotopic bone [3]
Fibroblasts, osteoblasts and chondroblasts come from same precursors
Tendon fibroblast differentiate into chondrocytes / hypertrophic chondrocyte and osteoblasts via COX-2
Pro-inflammtory cytokines like prostaglandin E2 induces osteoblasts to differentiate
Define sharpey fibres [1]
Sharpey’s fibres: are a matrix of connective tissue consisting of bundles of strong predominantly type I collagen fibres connecting periosteum to bone.
Label A
sharpey fibres
Describe enthesitis pathogenesis:
Normal enthesitis insertion occurs at a location with lots of which structure? [1]
How does this influence enthesitis pathogenesis? [3]
Normal enthesis inserts into porous bone at a location with lots of small transcortical vessels (TCV)
Mechanical trauma; TCVs become inflammed:
* Vasodilation
* Efflux of immune cells (neutrophils)
* Osteoblasts form bone at enthesis - causes bone to be formed
Enthesitis is associated with which three conditions? [3]
Ankylosing spondylitis
Psoriatic arthritis
IBD
How do you treat enthesitis:
- If mechanical? [2]
- If Inflammatory [5]
Mechanical:
* RICE
* NDSAIDs
Inflammatory:
* Sulfasalazine
* Methotrexate
* Anti-TNF therapy (restricted use for severe autoimmune enthetitis)
* Local radiotherapy
* Corticosteroid injection
* Hyperosmolar dextrose (initiates proliferation of intrinsic fibroblasts - race to repair damage c.f. osteoblasts)
Which drug class is used for ankylosing spondylitis enthesitis? [1]
Anti-TNF treatment
What are the names for arteries that supply tendons (of the hands)? [1]
Vincular arteries
Explain pathophysiology of De Quervien tenosynovitis [3]
Fibrosis and narrowing of tendon sheath: extensor retinaculum
Around anatomical snuffbox
Causes tendons and sheath rubbing over radial styloid process
Thickening and narrowing of tendon sheath
Lymphocyte inflammation
State and describe the name for test of De Querviens tensynovitis [1]
Finkelstein test:
- Patient resting their forearm on a surface in a neutral position with the wrist hanging off and unsupported
- The examiner holds the patient’s thumb and passively flexes the thumb into the palm, causing the wrist to adduct (ulnar deviation), putting **strain on the APL and EPB tendons. **
- If this causes pain at the radial aspect of the wrist, the test is positive, indicating De Quervain’s tenosynovitis.
Treatment for tenosynovitis?
Treatments [4]
Surgery - for trigger finger [1] and De Quervains [1]
Treatment:
* RICE
* Splinting
* Anti-inflam
* Corticosteroids
Surgery:
* TF: cut annular ligament
* DQ: shave styloid processs or cut sheath
DMARD treatments for SLE? [4]
Cylcophosphamide
Mycophenolate mofetil
Methotrexate
Tacrolimus
Describe two biological DMARDs for SLE? [2]
Belimubab: inhibits BAFF (B cell activating factor)
Rituximab: CD20 blocker
Describe the role of Langerhan cells [3]
Dendritic cell - spine-like projections
Efficient at presenting antigen to CD4+ helper T-cell
Pick up antigens that enter the skin and transport them to the lymph node
Staining dendritic cells n epidermis in a patient with skin infection.
Name an allergen produced by dust mice [3]
How does it cause damage to airway epithelium? [1]
Der P1 is an enzyme allergen
from the faecal pellets
of the dust mite.
Der P1 breaks down components of tight junctions which helps it to cross mucosa.
Binds to mast cells and causes degranulation
What is Pemphigus Vulgaris? [2]
autoimmune disease caused by antibodies directed against desmoglein 3, a cadherin-type epithelial cell adhesion molecule
Antibody and complement binds to desmoglein 3: causes acantholysis (loss of coherence between epidermal cells due to the breakdown of intercellular bridges)
Describe the features of Immune Complex Mediated Vasculitis [4]
Antigen and antibody form an immune complex
This causes production of proteins and aggregation of platelets into micro thrombi
This results in:
* Deposition of fibrin
* Leaky vessel and extravasation of blood and oedema.
* The proteases degrade vessel BMZ
* Necrosis of the vessel wall
Allergic Contact Dermatitis pathogenesis? [3]
Promotion of Th1 response:
- Secretion of IL2, IL3, GM-CSF, IFNg and TNF
- This promotes a macrophage rich response
- Causes inflammation to the skin around 48 hours to 72 hours after the challenge
Describe formation of granulomas
Clonal T-cell expansion
Secretion of
Th1 cytokines:
IL-2, IFN-g, TNF causes the creation of macrophages
