Skin 2 - Blistering dermatoses Flashcards
What is pemphigus vulgaris?
Its autoimmune destruction of desmosomes between keratinocytes
What is pemphigus vulgaris due to?
IgG antibody against desmoglein (type II hypersensitivity)
What does pemphigus vulgaris present as?
skin and oral mucosa bullae
In pemphigus vulgaris, why is there suprabasal blisters?
Acantholysis (separation) of stratum spinosum keratinocytes (normally connected by desmosomes) results in suprabasal blisters.
In pemphigus vulgaris, why is there a tombstone appearance?
Basal layer cells remain attached to basement membrane via hemidesmosomes - tombstone appearance
In pemphigus vulgaris, why is there shallow erosions with dried crust?
Thin-walled bullae rupture easily (Nikolsky sign), leading to shallow erosions with dried crust.
In pemphigus vulgaris, why is there a fish net pattern?
Immunofluorescence highlights IgG surrounding keratinocytes in a fish net pattern.
What is bullous pemphigoid?
Autoimmune destruction of hemidesmosomes between basal cells and the underlying basement membrane
What is bullous pemphigoid due to?
Its due to IgG antibody against basement membrane collagen
What does bullous pemphigoid present as?
blisters of the skin, oral mucosa is spared 1) Basal cell layer is detached from the basement membrane 2) Tense bullae do not rupture easily; clinically milder than pemphigus vulgaris
In bullous pemphigoid, what does immunofluorescence show?
it highlights IgG along basement membrane (linear pattern)
What is dermatitis herpetiformis?
Autoimmune deposition of IgA at the tips of dermal papillae
What does dermatitis herpetiformis present?
as pruritic vesicles and bullae that are grouped (herpetiform)
Dermatitis herpetiformis has a strong association with what?
celiac disease; resolves with gluten-free diet
What is erythema multiforme?
Hypersensitivity reaction characterized by targetoid rash and bullae
What is the targetoid appearance due to?
central epidermal necrosis surrounded by erythema
Erythema multiforme is most commonly associated with what?
HSV infection
Aside form HSV infections, what do the other associations include?
Mycoplasma infection, drugs (penicillin and sulfonamides), autoimmune disease (eg SLE), and malignancy
What is Steven Johnsons syndrome?
EM with oral mucosa/lip involvement and fever is termed Stevens Johnson syndrome (SJS)
What is toxic epidermal necrolysis?
It is a severe form of SJS characterized by diffuse sloughing of skin, resembling a large bum; most often due to an adverse drug reaction
