Dyshidrotic Eczema (Pompholyx, Palmoplantar Eczema)
Dyshidrotic eczema is a palmoplantar spongiotic dermatitis of multifactorial etiology (atopy, both irritant and allergic contactants, drug- or UV-induced, idiopathic, etc.) arising on the sides of the fingers, and less commonly the toes, as well as more variably arrayed on the palms and soles. The clinical morphology consists of pinpoint deep-seated papules that rapidly evolve into vesiculobullous lesions. Fox originally described “dyshidrosis” in 1873, as “sago grain-like vesicles” developing on non-erythematous skin of the fingers and toes. He erroneously implied a sudoriferous pathogenesis, further misconstrued as a “nervous debility” that altered sweat production. In 1876, Hutchinson largely ignored this description, invoking the term “cheiro-pompholyx” for numerous vesicles and multilocular bullae occurring frequently on the hands. In sum, the name “dyshidrosis” is misleading; the condition has no relation to dysfunction in eccrine glands or to sweating, and it may indiscriminately occur in a palmoplantar distribution.