How is morphology of allergic contact dermatitis?

➢ skin involvement in contact dermatitis is limited to sites of direct contact with the triggering agent ➢ whereas in other forms of eczema, lesions may be widely distributed. ➢ Spongiosis, or epidermal edema, characterizes all forms of acute eczematous dermatitis—hence the synonym spongiotic dermatitis. ➢ Edema fluid seeps into the epidermis, where it splays apart keratinocytes ➢ Intercellular bridges are stretched and become more prominent and are easier to visualize. ➢ These changes are accompanied by a superficial perivascular lymphocytic infiltrate, edema of dermal papillae, and mast cell degranulation. ➢ Eosinophils may be present and are especially prominent in spongiotic eruptions provoked by drugs, but in general the histologic features are similar regardless of cause, emphasizing the need for careful clinical correlation.