Skin-nontumor / Clinical Dermatology - Dermatitis herpetiformis

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Skin-nontumor / Clinical Dermatology

Blistering disorders

Dermatitis herpetiformis

Reviewer: Mowafak Hamodat, MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns, Canada (see Reviewers page)
Revised: 26 August 2011, last major update July 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Uncommon autoimmune blistering disorder associated with gluten-sensitive enteropathy; very pruritic (eMedicine, J Am Acad Dermatol 2011;64:1017)
● Involves extensor surfaces of elbows, knees, buttocks and back; also chest, axillae, neck, posterior shoulder and extensor aspects of the limbs; may involve hairless skin and oral mucosa

Terminology
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● Also called keratosis follicularis

Epidemiology
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● Ages 20-39 years; more common in males

Treatment
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● Dapsone, 50-200 mg/day; causes dramatic response, so the drug is administered for diagnostic and therapeutic purposes
● Rash returns 2-3 days after Dapsone is discontinued
● Gluten-free diet may cause prolonged remission in some patients or lower daily Dapsone requirement in others

Clinical description
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● “Herpetiform” because vesicles are small (pinhead sized) and grouped symmetrically, as with herpes
● May appear as erosions due to intense scratching

Clinical images
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Various images

Micro description
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● Subepidermal multilocular blister with papillary neutrophilic microabscesses that may contain eosinophils, basal cell vacuolization
● Dermal infiltrate is mixed, with lymphocytes, histiocytes and abundant neutrophils
● Karyorrhexis (nuclear dust within dermis) is characteristic
● No vasculitis

Micro images
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Subepidermal blister with microabscess

Granular IgA deposits in the dermal papillae

Virtual slides
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Dermatitis herpetiformis

Positive stains
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● Granular IgA pattern in dermal papillae by direct immunofluorescence
● No circulating antibodies

Differential diagnosis
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● Bullous pemphigoid: large tense blisters on flexor surfaces, trunk, intertriginous regions and mucosa; no microabscesses
● Linear IgA dermatosis: homogenous band of IgA at the dermal-epidermal junction; no anti-endomysial or anti-tissue transglutaminase IgA antibodies; not gluten sensitive

End of Skin-nontumor / Clinical Dermatology > Blistering disorders > Dermatitis herpetiformis

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