2- bullous disorders Flashcards
what are bullous disorders?
bullous = blisters
- these are group of blistering diseases caused by autoimmune antibodies attacking target somewhere in skin
what is pathophysiology of bullous pemphigoid?
anti-hemidesmosome antibodies (IgG) react w antigens of hemidesmosomes (which are anchoring basal cells of epidermis at desmo-epidermis junction)
= this attack causes activation of complement system & tissue damage, separating the 2 layers making a blister
what is clinical presentation of bullous pemphigoid?
before blister appears… can get itch or erythematous plaques weeks to months before blister
blister = is deep so thick roof less likely to burst (which if pops leaves erosions & does not scar), blister is large, tense, extremely itchy on erythematous base
*typically at flex regions
is nikolsky signs positive or negative in bullous pemphigoid?
negative (it’s if push blister it spreads further)
what is investigation for bullous pemphigoid?
get biopsy of edge of blister and send for immunofluorescence = which highlights antibodies & antigens showing liner IgG complement deposited at basal membrane
- also histology showing lots of eosinophils in blisters
what is management of bullous pemphigoid?
local disease = high potency topical steroid (dampens inflammation)
systemic disease = oral steroids + tetracycline antibiotics + antihistamine
(start with oral prednisolone as fast acting immunosuppressant then change to doxycycline as immunosuppressant)
*if no response to these then immunosuppression like azathioprine or methotrexate
what is pemphigus vulgaris?
a rare but severe autoimmune bullous disease (in all ages i think)
what is pathophysiology of pemphigus vulgaris?
type II hypersensitivity - also IgG antibodies but against desmosomes that hold keratinocytes together
makes keratinocytes drift apart = called acantholysis
what is clinical presentation of pemphigus vulgaris?
intraepidermal split so superficial so blisters pop easily so present as shallow erosions, painful
- commonly affect mucosa like mouth, resp etc then also affect skin like scalp, face, axillae, groin
is nikolsky sign positive or negative for pemphigus vulgaris?
positive
= when can press blister and moves along skin
what are investigations for pemphigus vulgaris?
= biopsy of blister and do immunofluorescence (highlights antibodies at keratinocytes = chicken wire pattern)
what is treatment of pemphigus vulgaris?
painful so might want topical anaesthetic
also topical steroids to treat inflammatory stuff
systemic = immunosuppression like prednisolone, azathioprine etc
what is dermatitis herpetiformis?
= autoimmune blister disorder associated with coeliac disease (subepidermal blisters)
- affects all ages
what is pathophysiology of dermatitis herpetiformis?
not well understood, IgA antibodies involved at cross reaction somewhere at dermal papillae
what is clinical presentation of dermatitis herpetiformis?
- small, very itchy blisters, symmetrical on erythematous & swollen base (itch can precede blisters)
- on extensor sides like elbows, knees, buttocks
what are investigations for dermatitis herpetiformis?
- bloods like IgA, anti-TTG
- biopsy then immunofluorescence (highlights dermal papillae)
what is management of dermatitis herpetiformis?
= avoid gluten!
1st line = dapsone
2nd line = topical steroids
