Blistering Disorders B&B Flashcards
what is the hallmark of pemphigus disorders?
pemphig = blister (Greek)
hallmark = acantholysis: loss of connections (usually desmosomes) between keratinocytes —> round, free-floating keratinocytes
involves mucous membranes (mouth) and skin
most common is pemphigus vulgaris (vulgaris = “common”), also pemphigus foliaceus, IgA pemphigus, paraneoplastic pemphigus
how will histology of pemphigus vulgaris appear?
autoantibodies against desmoglein —> acantholysis: loss of connections (desmosomes) between keratinocytes
“rounded” keratinocytes are seen detached/freely floating in epidermis
what is the cause of pemphigus vulgaris? where in the epidermis does this occur?
Type II hypersensitivity, autoantibodies against desmoglein (component of desmosomes) —> acantholysis (loss of connection between keratinocytes, free-floating and rounded)
disrupts connections in the stratum spinosum, allowing fluid to collect above the basal layer
Pt is a 45yo F presenting with an outbreak of large, flaccid bullae that easily burst. Most have ruptured and scabbed. The skin slips off with a genital tug. There are also numerous oral bullae and ulcerations. The pt complains of pain while chewing and swallowing. Biopsy shows rounded, free-floating keratinocytes in the stratum spinosum. What is the diagnosis and the cause of this disorder?
pemphigus vulgaris: Type II hypersensitivity, autoantibodies against desmoglein (component of desmosomes) in stratum spinosum —> acantholysis (loss of connection between keratinocytes), occurs mostly in adults (30-60)
Nikolsky’s sign = skin slips off with gentle tug
what type of hypersensitivity reaction is pemphigus vulgaris?
Type II hypersensitivity - autoantibodies against desmoglein (component of desmosomes) in stratum spinosum —> acantholysis (loss of connection between keratinocytes)
what are 3 causes of a positive Nikolsky’s sign?
Nikolsky’s sign = skin slips off with gentle tug, due to loss of connections between keratinocytes
- pemphigus vulgaris (autoantibodies against desmoglein) - adults
- staph. aureus scalded skin syndrome - children
- Stevens-Johnson syndrome - medication reaction
what is the classic immunofluorescent finding of pemphigus vulgaris?
Type II hypersensitivity - autoantibodies against desmoglein (component of desmosomes) in stratum spinosum —> acantholysis (loss of connection between keratinocytes)
shows positive IgG in a reticular (net) pattern because the autoantibodies are binding all around the borders of the keratinocytes
what is the cause of bullous pemphigoid?
autoantibodies against hemidesmosomes (between epithelial cells and basement membrane)
bullae are subepidermal
how do the bullae of bullous pemphigoid differ from those of pemphigus vulgaris?
pemphigus vulgaris = autoantibodies against desmosomes (between keratinocytes) —> flaccid, rupturing bullae
bullous pemphigoid = autoantibodies against hemidesmosomes (between epithelial cells and basement membrane) —> tense, intact bullae
how can immunofluorescence differentiate between pemphigus vulgaris and bullous pemphigoid?
pemphigus vulgaris = autoantibodies against desmosomes (between keratinocytes) —> reticular (net) pattern of IgG immunofluorescence
bullous pemphigoid = autoantibodies against hemidesmosomes (between epithelial cells and basement membrane) —> linear pattern of IgG immunofluorescence, following basement membrane
how does the clinical presentation of pemphigus vulgaris differ from that of bullous pemphigoid?
pemphigus vulgaris = autoantibodies against desmosomes (between keratinocytes) —> occurs in adults (30-60) with flaccid, rupturing bullae, often involves mouth, +Nikolsky’s sign (skin slips off), increased mortality due to immunosuppressants + infection risk with rupturing bullae
bullous pemphigoid = autoantibodies against hemidesmosomes (between epithelial cells and basement membrane) —> occurs in elderly with tense bullae, rarely involves mouth, (-) Nikolsky’s, less morality risk (less rupturing)
with what condition is dermatitis herpetiformis, and how does it present?
associated with celiac disease, caused by IgA deposition in dermal papillae
—> herpes-like lesions on skin (papules/vesicles in bilateral groups) which are pruritic, classically on extensors (knees, elbows)
Pt is a 27yo F presenting to her dermatologist with concern of an itchy rash on bilateral elbows. The rash looks similar to a picture of a herpes rash she found on the internet and she is concerned. PMH includes celiac disease and a pollen allergy. You take a biopsy, which shows microabscesses and neutrophils at the dermal papillae. What is the most likely cause?
dermatitis herpetiformis: associated with celiac disease, caused by IgA deposition in dermal papillae
—> herpes-like lesions on skin (papules/vesicles in bilateral groups) which are pruritic, classically on extensors (knees, elbows)
what would immunofluorescence of a skin biopsy from a patient with dermatitis herpetiformis reveal?
associated with celiac disease, caused by IgA deposition in dermal papillae —> herpes-like pruritic rash on extensors
IF shows IgA deposition at tips of dermal papillae
