Dermatitis Herpetiformis

Synonym: Duhring's disease.

Clinical:

■ Dermatitis herpetiformis is characterized by a symmetric extremely pruritic papulovesicular eruption on the extensor extremities (Fig. 6A).

■ A diffuse "herpetiform" distribution of lesions that are preceded by stinging sensation can also be seen (Fig. 6B). The mean age of patients is 40.

■ Dermatitis herpetiformis is associated with gluten-sensitive enteropathy in up to 90% of patients, but most patients are asymptomatic.

Histology (Figs. 6D and E):

■ Infiltration of the papillary tips with neutrophils (micro-abscesses), diagnostic of dermatitis herpetiformis

Differential Diagnosis:

Bullous lupus erythematosus; linear IgA bullous disease. A

rare variant of vasculitis, pustular vasculitis, has not only papillary dermal pustules, but also vasculitis involving the papillary dermal vessels.

Immunofluorescence:

■ DIF: granular IgA in papillary tips on perilesional skin of dermatitis herpetiformis (Fig. 6C)

■ IIF: circulating IgA antibodies to papillary tip immuno-reactants not seen

MUCOUS MEMBRANE PEMPHIGOID/CICATRICIAL PEMPHIGOID

Antigens:

■ Circulating antibodies to endomysium of smooth muscle, gliadin, and thyroid microsomal proteins are present, but are probably not directly pathogenic.

Pathophysiology:

■ IgA deposits in skin promote neutrophil recruitment to basement membrane zone, where proteases are released and degrade the basement membrane zone proteins, leading to blister formation.

Clinicopathologic Correlation:

Clinical Feature

Pathologic Feature

Location on extensor elbows,

Exposed areas likely to be traumatized

knees

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