Dermatitis herpetiformis is a rare, chronic, markedly pruritic, papular, vesicular, and bullous skin disease of unknown etiology. It is probably an autoimmune disease and activated via the alternate complement pathway. The patient describes the itching of a new blister as a burning itch that disappears when the blister top is scratched off. The severe scratching results in the formation of excoriations and papular hives, which may be the only visible pathology of the disease. Individual lesions heal, leaving an area of hyperpigmentation that is very characteristic. The typical distribution of the blisters or excoriations is on the scalp, sacral area, scapular area, forearms, elbows, and thighs. In severe cases, the resulting bullae may be indistinguishable from pemphigus or bullous pemphigoid.
The duration of dermatitis herpetiformis varies from months to as long as 40 years, with periods of remission scattered in between. The illness is associated with nontropical sprue.
Laboratory tests should include fixed tissue and fresh tissue biopsy. The latter shows in most cases granular IgA in the dermal papillae, along with the third component of complement (C3). The finding of endomysial antibodies in the blood is highly specific for the disease. A blood cell count usually shows an eosinophilia.
Herpes gestationis (see Figi.i. 26-11.D-E) is a vesicular and bullous disease that occurs in relation to pregnancy. It usually develops during the second or the third trimester and commonly disappears after birth, only to return with subsequent pregnancies. The histologic features are believed significantly distinctive so that this disease can be separated from dermatitis herpetiformis. Immunologic findings of C3 bound to the basement membrane of the epidermis and occasional IgG deposition may be significant. Therapy with systemic corticosteroids is usually indicated.
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