Chapter 60 EBA Flashcards
African Americans in the southeastern USA who have either EBA or bullous SLE have high incidence of _____ phenotype
HLA-DR2
relative risk 13.1
Associated with autoimmunity to collagen ____
collagen type VII within anchoring fibril structures located at DEJ
IgG autoantibodies to type VII collagen associated with paucity of _____
paucity of normal anchoring fibrils at BMZ separating epidermis from dermis ad poor epidermal-dermal adherence
paucity of normal anchoring fibrils associated w/ 2 similar clinical phenotypes
1)___ 2)___
EBA
dystrophic hereditary EB
dystrophic EB - genetic defect in the gene that encodes for ____
type VII collagen a chains
gene in short arm of chrom 3
EBA pathway leading to reduction of anchoring fibrils - may be type VII collagen a chains decorated w/ EBA autoantibodies cannot form _____
triple helical structures and stable anchoring fibrils
most EBA autoantibodies recognize 4 predominant antigenic epitopes within the ____ domain
NC-1 domain
not helical and NC-2
3 tests ?
skin biopsy for H&E
2nd biopsy juxtaposed to a lesion but on normal skin for DIF
blood draw (antibodies against BMX and/or type VII collagen - IIF or ELISA)
cutaneous lesions of classic EBA
acral distribution
heals w/ scarring and milia
(reminiscent of PCT when mild, recessive dystrophic EB when severe)
differentiate classic EBA from PCT
do not have hallmarks of PCT - hirsutism, photodistribution of eruption, scleroderma like changes and urinary porphyrins WNL
BP like presentation?
- widespread vesiculobullous
- trunk, central body, skin folds and flexural (accentuation), extremities
- mucosal
- urticarial plaques
- pruritus
cicatricial pemphigoid like ?
erosions and scars on mucosal of mouth, upper esophagus, conjunctiva, anus or vagina w/ or w/o on glabrous skin
brunsting-perry pemphigoid like?
localized to head and neck
minimal or no mucosal
IgA bullous dermatosis like ?
subepidermal bullous eruptin
neutrophilic infiltrate
linear IgA deposits at BMZ (DIF)
tense vesicles in annular fashion
mucosal is frequent, severe in childhood EBA but more favorable prognosis than adult
systemic disease most frequently associated w/ EBA
IBD
predominant IG class in IF
IgG
also IgA, IgM, factor B, properdin
DIF feature distinguishing PCT from EBA is ?
PCT demonstrates immune deposits around dermal BV
gold standard for Dx
immunoelectron microscopy : immune deposits within sublamina densa zone
Indirect salt split skin IF
IgG on epidermal roof - BP
IgG dermal side - EBA or bullous SLE (rule out by serology and clinical )
direct salt split skin IF
immune deposits on dermal side by routine DIF method using fluorescein-conjugated antihuman IgG
Western immunoblotting ?
antibodies bind to 290 kDa BM proteins containing type VII collagen (a chain)
and bind to 145 kDa - amino terminal globular NC-1 domain of type VII collagen a chain
ELISA used ___
NC-1
Differential Dx
PCT
Pseudoporphyria cutanea tarda
BP
CP
Diagnostic criteria for EBA
- bullous disorder w/ in clinical spectrum
- no family hx of bullous d/o
- histo of subepidermal blister
- IgG w/ in DEJ (positive DIF)
- IgG localized to lower lamina densa and/or sublamina densa zone of DEJ (perilesional skin by DIF)
severe EBA may develop _____
fibrosis of hands w/ decreased ROM of palms and digits
fibrosis on soles and feet = difficulty walking
classic mechanobullous form are often refractory to high doses of ___
systemic CCS, azathioprine, MTX, cyclophosphamide
somewhat helpful in controlling
first line drug
colchicine
common side effect of colchicine
diarrhea
photopheresis and mechanism ?
lengthens suction blistering times suggesting improvement in epidermal-dermal adherence
tx for recalcitrant EBA
rituximab
