Chapter 60 EBA

Question 1

African Americans in the southeastern USA who have either EBA or bullous SLE have high incidence of _____ phenotype

Answer 1

HLA-DR2

relative risk 13.1

Question 2

Associated with autoimmunity to collagen ____

Answer 2

collagen type VII within anchoring fibril structures located at DEJ

Question 3

IgG autoantibodies to type VII collagen associated with paucity of _____

Answer 3

paucity of normal anchoring fibrils at BMZ separating epidermis from dermis ad poor epidermal-dermal adherence

Question 4

paucity of normal anchoring fibrils associated w/ 2 similar clinical phenotypes
1)___ 2)___

Answer 4

EBA

dystrophic hereditary EB

Question 5

dystrophic EB - genetic defect in the gene that encodes for ____

Answer 5

type VII collagen a chains

gene in short arm of chrom 3

Question 6

EBA pathway leading to reduction of anchoring fibrils - may be type VII collagen a chains decorated w/ EBA autoantibodies cannot form _____

Answer 6

triple helical structures and stable anchoring fibrils

Question 7

most EBA autoantibodies recognize 4 predominant antigenic epitopes within the ____ domain

Answer 7

NC-1 domain

not helical and NC-2

Question 8

3 tests ?

Answer 8

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)

Question 9

cutaneous lesions of classic EBA

Answer 9

acral distribution
heals w/ scarring and milia
(reminiscent of PCT when mild, recessive dystrophic EB when severe)

Question 10

differentiate classic EBA from PCT

Answer 10

do not have hallmarks of PCT - hirsutism, photodistribution of eruption, scleroderma like changes and urinary porphyrins WNL

Question 11

BP like presentation?

Answer 11

• widespread vesiculobullous
• trunk, central body, skin folds and flexural (accentuation), extremities
• mucosal
• urticarial plaques
• pruritus

Question 12

cicatricial pemphigoid like ?

Answer 12

erosions and scars on mucosal of mouth, upper esophagus, conjunctiva, anus or vagina w/ or w/o on glabrous skin

Question 13

brunsting-perry pemphigoid like?

Answer 13

localized to head and neck

minimal or no mucosal

Question 14

IgA bullous dermatosis like ?

Answer 14

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

Question 15

systemic disease most frequently associated w/ EBA

Answer 15

IBD

Question 16

predominant IG class in IF

Answer 16

IgG

also IgA, IgM, factor B, properdin

Question 17

DIF feature distinguishing PCT from EBA is ?

Answer 17

PCT demonstrates immune deposits around dermal BV

Question 18

gold standard for Dx

Answer 18

immunoelectron microscopy : immune deposits within sublamina densa zone

Question 19

Indirect salt split skin IF

Answer 19

IgG on epidermal roof - BP

IgG dermal side - EBA or bullous SLE (rule out by serology and clinical )

Question 20

direct salt split skin IF

Answer 20

immune deposits on dermal side by routine DIF method using fluorescein-conjugated antihuman IgG

Question 21

Western immunoblotting ?

Answer 21

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

Question 22

ELISA used ___

Answer 22

NC-1

Question 23

Differential Dx

Answer 23

PCT
Pseudoporphyria cutanea tarda
BP
CP

Question 24

Diagnostic criteria for EBA

Answer 24

• 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)

Question 25

severe EBA may develop _____

Answer 25

fibrosis of hands w/ decreased ROM of palms and digits

fibrosis on soles and feet = difficulty walking

Question 26

classic mechanobullous form are often refractory to high doses of ___

Answer 26

systemic CCS, azathioprine, MTX, cyclophosphamide

somewhat helpful in controlling

Question 27

first line drug

Answer 27

colchicine

Question 28

common side effect of colchicine

Answer 28

diarrhea

Question 29

photopheresis and mechanism ?

Answer 29

lengthens suction blistering times suggesting improvement in epidermal-dermal adherence

Question 30

tx for recalcitrant EBA

Answer 30

rituximab