Immunobullous Disorders

Question 1

Name three immunobullous disorders

Answer 1

• pemphigus vulgaris
• bullous pemphigoid
• dermatitis herpetiformis

Question 2

Describe the aetiology of pemphigus vulgaris

Answer 2

Rare autoimmune disease IgG auto-antibodies are made against desmoglein 1/3 the protein in desmosomes which attach cells in the prickle cell layer.

Question 3

What happens in pemphigus vulgaris when immune complexes form on the cell surface

Answer 3

Complement activation and protease release leads to acantholysis where keratinocytes separate from each other, producing fluid filled blisters

Question 4

Where does pemphigus vulgaris typically affect?

Answer 4

Scalp, face, axillae, groin

Question 5

How does pemphigus vulgaris present?

Answer 5

Flaccid vesicles/bullae that rupture to leave a raw area - mucosal involvement is common

Question 6

What sign is positive in pemphigus vulgaris?

Answer 6

Nikolsky sign - top layers of the skin slip away from the lower layers when rubbed - suggest a cleavage in the epidermis

Question 7

What would immunofluoresence show in pemphigus vulgaris?

Answer 7

Cell surface bound IgG net-like pattern in epidermis

Question 8

How is pemphigus vulgaris treated?

Answer 8

Systemic therapy - high does weaning course of oral steroids in combination with an immunosuppressant

Question 9

Describe the pathology of bullous pemphigoid

Answer 9

Circulating IgG reacts with antigens of the hemidesmosomes at the DEJ leading to complement activation and tissue damage - leading to cleavage of skin at DEJ leading to sub epidermal blisters

Question 10

How does bullous pemphigoid typically present

Answer 10

Large bull on erythamtous base, blister to leave erosions, may be localised to one area or widespread on trunk and limbs. Presents will itchy plaques and papules.

Question 11

Who is often affected by bullous pemphigoid?

Answer 11

Elderly people

Question 12

What is the aetiology of bullous pemphigoid?

Answer 12

IgG autoantibodies to basement membrane antigens

Question 13

What will bullous pemphigoid look like on immunofluorescent labelling?

Answer 13

Linear IgG at basement membrane

Question 14

Is bullous pemphigoid Nikolsky positive or negative?

Answer 14

Negative

Question 15

How is Bullous pemphigoid managed?

Answer 15

Localised disease - topical super potent steroids

Widespread - Oral steroids and immunosuppressant/tetracyline and nicotinamide

Question 16

Describe the aetiology of dermatitis herpetiformis

Answer 16

IgA auto-antibodies to gluten tissue trans-glutaminase in the gut and epidermis. IgA targets gliadin in gluten but cross reacts with connective tissue matrix proteins

Question 17

What happen in dermatitis herpetiformis when immune complexes form?

Answer 17

Activation of complement and neutrophil chemotaxis leads to intensely itchy lesion & papillary dermal micro abscesses

Question 18

What disease do 75% of patients with dermatitis herpetiformis have?

Answer 18

Coeliac disease

Question 19

How will dermatitis herpetiformis present?

Answer 19

Itchy vesicles or small blisters usually on extensors and bum.

Question 20

How will dermatitis herpetiformis appear on immunofluorescence?

Answer 20

Granular IgA in dermal papillary tips

Question 21

What is the treatment for dermatitis herpetiformis?

Answer 21

Gluten free diet & oral dapsone (antibiotic thought to inhibit neutrophil migration)