OM- Immune mediated disease

Question 1

What is an epitope?

Answer 1

This is the site on the antigen of a protein where the antibody binds to.

Question 2

Why do diseases affecting the skin also affect the oral or genital mucosa?

Answer 2

Because they come from the same precursor tissue
so they share many common epitopes and antigens.

Question 3

What is desmoglein?

Answer 3

A Protein that holds the cells together.

Question 4

What is the difference between a vesicle and a blister ?

Answer 4

Vesicles 1-2mm
Blisters >2mm

Question 5

How do vesicles form ?

Answer 5

1. autoantibody attack on desmoglein & hemidesome attachments
2. Loss of cell to cell adhesion
3. Formation of a split in the cell which fills with inflammatory exudate.
4. This forms vesicles/ blisters

Question 6

What disorder is pictured?

Answer 6

Eythema multiforme

Question 7

Describe the aetiology of erythema multiforme.

Answer 7

1.Antigen and antibody bind within circulation producing a large complex that is unable to pass through the capillaries.

2. Complex gets wedged activating complement.
3. This causes a perivascular inflammatory response.
4. Eventually causing blistering and ulceration of the tissue.

Question 8

What disorder is erythema multiforme known as at its most severe?

Answer 8

Stevens Johnson syndrome.

Question 9

What is the oral presentation of erythema multiforme?

Answer 9

Target lesions on the skin
Crusted of the lips due to rusting and healing of the lesions on the oral mucosa.
Coalescent areas of ulceration internally- (commonly lasts 2-3 weeks then has an ulcer free period for 1- 6 months)

Question 10

How do we treat patients with erythema multiforme?

Answer 10

Medicines- systemic steroids (to prevent antigen and antibody binding & so activation of complement= 60mg prednisolone.
Systemic Acylovir
Encourage fluid intake- May need IV fluid if the ulcers are preventing hydration
Encourage analgesia

Question 11

When would systemic acyclovir be used for treatment of erythema mulitforme?

Answer 11

If there is recurrence of ulcers. This can be used to prevent the herpes simplex replicating that is causing the type 3 hypersensitivity

Question 12

What type of reaction is erythema multiforme and what triggers it?

Answer 12

Type 3 hypersensitivity reaction which is triggered by the reactivation of herpes simplex virus.

Question 13

What is this immune mediated disease?

Answer 13

Angina bullosa Haemorrhagica- a tight blood filled blister on the oral mucosa.

Question 14

On what common sites would you find Angina Bullosa haemorrhagica?

Answer 14

Buccal mucosa and soft palate

Question 15

What are some triggers of angina bullosa haemorrhagica?

Answer 15

Minor trauma/ steroid inhalers /eating

Question 16

What are some characteristics of angina bullosa haemorrhagica.

Answer 16

• Rapid onset
• Lastsa about an hour then bursts (letting blood stained fluid into the mouth)
• Left with an area of ulceration as it heals.
• Heals without scarring within a few days.

Question 17

How do we treat patients with angina bullosa haemorrhagica ?

Answer 17

Symptomatically
Difflam spray
Chlorohexidine mouthwash.

Question 18

What are hemi-desmosones

Answer 18

These attach the basement membrane to the connective tissue.

Question 19

What is this?

Answer 19

Pemphigoid- thick walled blisters that persist for some time. They can be clear or blood filled (Leakage of red blood cells if there is damage to the connective tissues)

Question 20

What is this?

Answer 20

Pemphigus- where there is Mucosal erosion and mucosal surface loss.

Question 21

Compare the formation of pemphigus and pemphigoid?

Answer 21

Pemphigoid- Antibodies attack the hemi-desmosomes causing separation of basement membrane and connective tissue. The full epithelium is released. The fluid and inflammatory exudate fills the epidermis and connective tissue.
Pemphigus- antibodies attaack the desmosomes (Join cells together) Intraepithelial bullae are produced. The fluid filling between the cells eventually causes the cells to seperate and move away. We then get the thinning of cells and loss of epithelium.

Question 22

Compare the sites where pemphigus and pemphigoid are found?

Answer 22

Pemphigoid
On skin- bullous pemphigoid
Affecting all mucous membranes- mucous membrane pemphigoid.
Mucosal pemphigoid with scarring- Cicatricial pemphigoid.

The most common form of Pemphigus is pemphigus vulgaris. This is first seen on the oral mucosa and then in skin.

Question 23

How do we biopsy to test for pemphigus or pemphigoid?

Answer 23

Using a perilesional biopsy

Question 24

Compare what we see histopathologically with pemphigus and pemphigoid?

Answer 24

Pemphigus - A subepithelial split between the epithelial and connective tissue junction.

Pemphigoid- A supra-basal split.

Question 25

What risks are associated with pemphigus and pemphigoid ?

Answer 25

Pemphigoid- when the blister ruptures we get exposed connective tissue (risk of infection due to the lost epithelial barrier) & the loss of exudate if enough blisters burst can cause dehydration.

Pemphigus- The loss of epithelial covering leads to fluid loss and infection risk.

Question 26

Compare the treatment of pemphigus and pemphigoid.

Answer 26

Pemphigoid- immunosupressants to prevent the antibody causing the disease.
Steroids.
Immune modulating drugs (Azathioprine)

Pemphigus- High dose steroids .