Dermatitis Herpetiformis

Question 1

Most commonly affected populations for dermatitis herpetiformis

Answer 1

• Northern europeans

Question 2

Average age of onset for dermatitis herpetiformis?

Answer 2

30-40 y/o

Question 3

Genetic associations of dermatitis herpetiformis?

Answer 3

HLA-DQ2 >>> HLA-DQ8

Question 4

DH is strongly a./w what other diseases?

Answer 4

autoimmune diseases (Hashimoto’s, pernicious anemia, addisons)

Question 5

Pathogenesis of dermatitis herpetiformis in skin?

Answer 5

1. gluten broken into gliadin in gut
2. gliadin is broken down by TTG2 in GI tract
3. deaminated gliadin and TTG2 connect to form TTG2-gliadin complex (antigen)
4. IgA antibodies bind to this complex–> neutrophil recruitment and damage of intestines
5. epitrope spreading results in IgA antibodies against TTG3 (epidermal transglutaminase) that bind within dermal papillae

6. neutrophils recruited to dermal papillae and release MMP/elastase leading to subepidermal blisters

Question 6

Where will subepidermal blisters of dermatitis herpetiformis be most prominent on histopath?

Answer 6

above dermal papillae (thats where most of neuts are located)

Question 7

Clinical presentation of dermatitis herpetiformis:

Answer 7

• extremely itchy herpetiform vesicles arising on urticarial plaques
• vesicles can easily rupture with scratching commonly leaving only excoriations on exam

Question 8

Classic distribution of dermatitis herpetiformis:

Answer 8

• Extensor extremities, buttocks, and back/neck

Question 9

What can you see on palms/soles of dermatitis herpetiformis patients?

Answer 9

• hemorrhagic lesions

Question 10

What % of dermatitis herpetiformis patients have symptomatic GI disease? What % have some degree of gluten sensitivity?

Answer 10

• 20%

- >90%

Question 11

Histopathology of dermatitis herpetiformis:

Answer 11

• subepidermal bullae most pronounced above dermal papillae with neutrophilic papillitis

Question 12

DIF findings of dermatitis herpetiformis:

Answer 12

• granular IgA deposits in dermal papillae

Question 13

What are ideal biopsy sites for DH to get histology? DIF?

Answer 13

• biopsy an early blister for histology
• biopsy 1cm away from blister for DIF

Question 14

What testing needs to be done prior to initiating Dapsone?

Answer 14

Must check G6PD deficiency!!

Question 15

What antibodies are commonly present in dermatitis herpetiformis patients?

Answer 15

• IgA antiendomysial
• IgA anti TTG
• IgA anti gliadin

Question 16

Treatment for dermatitis herpetiformis:

Answer 16

Dapsone! rapid relief in 2-3 days

Question 17

Second line agent if you cant use dapsone for dermatitis herpetiformis?

Answer 17

sulfapyridine

Question 18

Will dapsone treat GI disease if dermatitis herpetiformis patients?

Answer 18

• no, need gluten free diet to do this

Question 19

How do you control skin disease, GI disease, and decrease GI lymphoma risk in patients with dermatitis herpetiformis?

Answer 19

• gluten free diet