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Dermatitis Herpetiformis (tier 2)
Dermatitis herpetiformis
is a subepidermal, vesiculo-bullous disorder. It is an immune disorder that is associated with gluten-sensitive enteropathy. The diagnosis is based on the demonstration of granular deposits of IgA in peri-lesional skin (beneath the basal lamina).
The initial lesion of dermatitis herpetiformis at the light microscopic level is an accumulation of neutrophils, with scattered eosinophils, in the tips of dermal papillae (S6C27P21-1-4, & S6C28P22-1-4)). Proteolytic enzymes derived from these infiltrates
digest the anchoring structures at the dermal-epidermal interface; as a consequence, a cleft forms at the tips of the affected dermal papillae. Progression is manifested by confluence of the clefts along the
dermal-epidermal interface; a blister forms. Migratory histiocytes in edematous dermal papillae are a feature of early lesions. In older lesions showing a necrotizing papillitis, some of the histiocytes of the
edematous dermal papillae are rounded in outline (they are activated) (S6C28P22-5).
The roof of the vesicle or bulla in lesions of DH shows a relatively intact epidermis with a normal keratin layer. The basal layer of the roof of the vesicle may be poorly
defined; the cells that abut upon the defect may be flattened, or they may assume features of cells of the superficial unit of the epidermis. The roof may show areas of spongiosis and even areas of spongiotic, or
reticulated, vesiculation (S6C27P21-5). Small, irregular, lytic defects in the epidermis over the tips of involved papillae contain neutrophils and
eosinophils.
The vesicle contains a meshwork of fibrin with loose infiltrates of neutrophils and eosinophils (S6C28P22-1).
The papillitis may progress to areas of papillary necrosis. The tips of affected papillae show fibrinoid necrosis. In addition, fibrin condenses over the inflamed papillae. The
breakdown of inflammatory cells (a leukocytoclastic phenomena with the formation of nuclear debris) may imbue a distinct basophilia to the affected connective tissue (S6C28P22-5 & 6). On this basis, one might anticipate a sclerosing reaction, somewhat similar to that seen in lesions of cicatricial pemphigoid, in
the reparative phase of old lesions of DH.
Carmisa C, Sharma HM: Vesicobullous systemic lupus erythematosus: report of two cases and a review of the literature. J Am Acad Dermatol 1983;9: 924-35.
Hall RP: The pathogenesis of dermatitis herpetiformis: recent advances. J Am Acad Dermatol 1987;16: 1129-44.
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