1.2 Blistering dermatoses Flashcards
dermatitis herpetiformis
- mech
- associated with what
- autoimmune IgA deposition on tips of dermal papillae
- form pruritic vesicles and bullae that are grouped (look like herpes)
- strong association with Celiac disease. treating Celiac (gluten free) will also treat dermatitis herpetiformis
mucous membrane pemphigoid (MMP)
- blistering of mucous membranes and sometimes skin’
- possible blindness
- majority of pts have Ab against BP 180, but some have Ab to Bp 230 or laminin 332
what is it?
- skin bullae. oral mucosa spared.
- bullae do not rupture easily
bullous pemphigoid
what can erythema multiforme progress to?
- Stevens-Johnson syndrome (SJS) if oral mucosa/lip and fever involved
- toxic epidermal necrolysis (TEN) is severe SJS
bullous pemphigoid has Ab against which 2 things?
Hemidesmosomes:
- BP 230–plakin protein, important for cytoskeleton architecture
- BP 180–Collagen type 17
how does SJS/TEN typically present?
- painful red macules on body, plus oral mucosa ulcers. rapidly evolves to bullae and necrosis
- preceded by Prodome of 1-14 days, flu-like symptoms
what is it?
- skin and oral mucosa bullae
- bullae rupture easily
pemphigus vulgaris
bullous pemphigoid
- clinical findings
- histology
- skin bullae. oral mucosa spared.
- bullae do not rupture easily (epidermal layer above blister is thick)
- histology: blister between epidermis and dermis. no ‘tombstone’ appearance.
Tx for pemphigus vulgaris
- autoimmune, so:
- prednisone
- azathioprine (6-MP)
- mycophenilate mofetil
- rituximab
Bullous pemphigoid
-mech
- autoimmune destruction of hemidesmosomes, between basal cells and dermis (basement membrane)
- IgG against hemidesmosomes
main components of basement membrane (4)
- hemidesmosomes
- lamina lucida
- lamina densa
- sublamina densa
ichthyosis vulgaris
- clinical findings
- associated with what
- ‘fish scales’ especially on shins
- dry skin
- associated with allergies, asthma
pemphigus vulgaris
-mech
- autoimmune destruction of desmosomes
- IgG against desmoglein (type 2 HSR)
- desmosome exist in stratum spinosum of epidermis, so blister forms in that layer
what is it?
-pruritic vesicles and bullae that are grouped, looks like herpes
dermatitis herpetiformis
erythema multiforme
-what causes it?
- cutaneous hypersensitivity reaction
1. viral infections most common: - HSV infection 50% (also mycoplasma)
2. Drug reaction - Abx, NSAIDs, sulfa drugs, antiepileptics
Epidermolysis Bullosa Acquisita (EBA)
- mutation in collagen 7 in sublamina densa
- rare autoimmune blistering disease
erythema multiforme
- mech
- clinical findings
“multiple erythematous rashes”
- hypersensitivity reaction
- “targetoid” rash–looks like targets because center is necrosed
pemphigus vulgaris
- clinical findings
- histology
- skin and oral mucosa bullae (blisters)
- blisters rupture easily (because epidermis superficial to blister is thin)
- histology: ‘tombstone’ appearance of stratum basalis
toxic epidermal necrolysis
severe form of stevens-johnson syndrome, which is erythema multiforme with lip/oral mucosa involvement, plus fever.
-usu drug reaction
what is in the lamina densa?
- collagen 4 and laminins
- most important laminin is laminin 332
what is Direct IF microscopy?
- tests for IgG and C3 bound to antigens in sample of patient’s skin cells
- test for pemphigus, etc
generalized atrophic benign epidermolysis bullosa (GABEB)
- mutated BP 180 protein (collagen 17)
- results in blistering skin
Nikolsky’s sign
- blisters easily expanded and erupted by rubbing.
- found in pemphigus vulgaris
erythema multiforme
-tx?
-topical corticosteroids
