Bullous and Autoimmune Diseases Flashcards
Name autoimmune skin diseases?
- Multisystem autoimmune diseases that affect the skin
e.g. systemic lupus erythematosus, systemic sclerosis - More localised (skin targetting) autoimmune diseases
e.g. chronic autoimmune urticaria, morphoea (synonym localised scleroderma), various autoimmune bullous diseases - Complex conditions in which autoimmunity is a major factor
e.g. psoriasis, vitiligo
What is lupus erythematosus??
Can be considered as a spectrum of skin diseases
(least to most likely to be associated with systemic
lupus erythematosus):
1. Chronic discoid lupus erythematosus and Tumid
lupus erythematosus
2. Subacute cutaneous lupus erythematosus
3. Acute cutaneous lupus erythematosus
What is a blister?
- A fluid-filled collection within the skin
- To be a blister, rather than oedema, it should be possible to use a
needle and release fluid. - The fluid can be clear, straw-coloured or bloody (if it is pus it is a pustule not a blister).
- A large blister is a bulla; if small it is a vesicle.
- Bullae can be unilocular or multilocular
Levels of blistering?
- The more superfcial a blister is the more likely it is to burst, leaving erosion often with crusting
- If intensely itchy blisters are often burst even when deeper.
1. Intra-epiderma
e.g. pemphigus, acute dermatitis, herpes simplex
2. Sub-epidermal
e.g. pemphigoid, DH, blistering porphyrias
Physical causes of skin blistering?
– Arthropod (often insect) bites
– Other mechanisms of arthropod reactions (e.g. blister
beetle)
– Burns
– Friction
Infectious causes of skin blistering?
Viral
* HSV – cold sores, eczema herpeticum
* VZV – chickenpox, zoster
* Coxsackie virus – hand-foot-and-mouth disease
Bacterial
* Staph aureus – bullous impetigo, SSSS
* Strep pyogenes – bullous cellulitis
Non infectious causes of skin blistering?
Genetic
– Epidermolysis bullosa (EB)
* Metabolic
– Porphyria cutanea tarda, other blistering porphyrias
* Drugs
– EM / Stevens-Johnson syndrome
– Toxic epidermal necrolysis (TEN)
– Fixed drug eruption
* Acute dermatitis
– Acute allergic contact dermatitis
– Pompholyx
– Phytophotodermatitis
Autoimmune causes of skin blistering?
– Intraepidermal
* Pemphigus (pemphigus = superficial)
– Subepidermal
* Bullous pemphigoid = deep
* Mucous membrane pemphigoid
* Pemphigoid gestationis
* Linear IgA disease
* Dermatitis herpetiformis
* EB acquisita
Invetstigation of blistering?
- Infection
- Bacterial microscopy & culture
- PCR – HSV, VZV
- Viral culture
- Serology - Porphyria
- Porphyrin studies - Contact dermatitis
- Patch testing - Autoimmune
- Biopsy with IMF
What is bullous pemphigoid?
- an autoimmune blistering skin condition
- Incidence approx 6 per 1,000,000
- Age >60 years in majority
- Usually generalised but 15%-30% localised bullae
Describe clinical features of bullous pemphigoid?
- Mucosal lesions usually restricted to the mouth (and only about half have mucosal lesions)
- Large tense bullae on normal skin or
erythematous base - Bullae burst to leave erosions (no scarring)
- Itchy erythematous plaques and papules may be the
presenting feature (pre-bullous) - Nikolsky sign negative
Pathogenesis of bullous pemphigoid?
- Patients circulating antibodies (IgG) react with antigens (e.g. BPAG1 & 2) in BM and hemidesmosomes anchoring basal cells to BM
- Resultant local complement activation and tissue damage leading to a subepidermal bulla
- Immunofluorescence shows linear IgG + complement deposited around the BM
Treatment of bullous pemphigoid?
Localised BP
* Topical corticosteroids
Generalised BP:
* Tetracyclines
* Oral corticosteroids
* Dapsone
* Azathioprine
* (Ciclosporin)
Prognosis of bullous pemphigoid?
- Chronic self-limiting course
- Duration varies from months to years
- Most patients achieve remission on
treatment within 3 – 6months
Describe chronic bullous dermatosis of childhood?
- Also dermoepidermal junction
cleavage; different age group from
pemphigoid - direct immunofluorescence
shows linear IgA (rather than the IgG
of pemphigoid)
