Bullous disorders Flashcards
causes of skin blistering
infection / inflamamtory
drugs/ toxins
congenital
autoimmune
trauma
endocrine
investigations of blistering
bacterial and viral swabs
porphyrin studies
patch testing
biopsy with iMF
Autoimmune blistering disorders
bullous pemphigoid
pemphigus vulgaris
dermatitis herpetiforms
why does the ksin blister
problems with whats holding the skin together
when epidermis seperates from dermis creating a space filled with fluid
what does the fluid inside the blister act as
a cushion helping to protect the damaged tissue underneath while it heals
level of blistering in pemphigoid and dermatitis herpetiforms
sub epidermal
level of blistering in pemphigus
intra epidermal
intraepidermal split features
roof of blister thin so will burst easily
intraepidermal
erosions on skin
deeper split features
whole epidermis forms roof of blister so remains sturdy
subepidermal
fluid filled
rules out pemphigus
more likly to be dh, pemphigoid
bullous pemphigoid features
generalised problem
subepidermal split
roof of blister formed by full thickness of epidermis
tense intact bullae
may get itchy raised areas of skin before blisters
pemphigoid v pemphigus
nikolsky sign- apply lateral pressure away from area of blistering, if superficial blister then can extend blister that way - pemphigus
pemphigoid sign is negative as deeper down
bullous pemphigoid pathology
producing antibodies attacking skin
antigens in basememt membrane
hemidesmosomes which hold basal layer of cells onto basement membrane are the targets so autoantibodies are attacking these
happening below epidermis at dermo epidermal junction
which circulating antibodies react with the antigens in bullous pemphigoid
IgG
investigations for bullous pemphigoid and pemphigus
diagnkstic biopsy
across edge of blister then cut in half- half with blister on it stain with h and e
non blister part send for IMF to detect for autoantibodies in skin
blood sample to look for circulating skin antibodies in serum
IMF
add a flourescene label antibody that will bind to autoantibody in skin and light up to show where they are
imf in bullous pemphigoid
linear band along dermo epidermal junction of egg
treatment for BP
Immmunosuppressants
generalised- oral steroids
localised- strong topical steroids
steroid sparing agents like tetracyclines
prognosis of BP
Chronic self- limiting course
Duration varies from months to years
Most patients achieve remission within 3 – 6months
pemphigus vulgaris charcateristics
rare
affects slightly younger patients
intra epidermal
split is higher so blisters more fragile
mucosal involvement is common - eyes, mouth, rectum etc
presents in mucosa first of all
oral mucosa most common site
erosions and flattened blisters more common
is nikolsy sign positive or negative in pemphigus vulgaris
positive
pathogenesis of pemphigus vulgaris
igg antibodies
target antigen is the desmosomes which are holidng all the keratinocytes so allows them to drift apart known as acantholysis
IMF in pemphigus
chicken wire pattern
outlines of keratinocytes lighting up
treatment for pemphigus
topical steroids/ anaesthetics as raw exposed skin so causes pain and infection risk
immunosuppression
plasmapheresis/ monoclonal antibodies in serious cases
prognosis in pemphigus
remit within 3-6 years majority of cases
mortality rate of 10-20%
dermatitis herpetiforms
all ages afffected- majoruty young adults
assoc with coeliac
small itchy blisters- vesicles
symmetricly distributed
extensor sites favoured- knees, elbows
sub epidermal
pathogenesis of dermatitis herpetiforms
IgA
cross react with transglutaaminse in skin causing release of inflammaotry mediators which cause dmaage at dermo epidermal junction
investigations in DH
blood tests for coeliac
histology
biopsy for h and e
endoscopy and biopsy if no known coelaic
IFM in DH
highlights the IgA in dermal papillae
treatment for DH
avoid gluten
symptomatic release for lesions- topical steroids
dapsone if not working
risk in coeliac disease
small bowel lymphoma
