Immunohistochemical Study of 2 Cases of Coxsackie A6-Induced Atypical Hand-Foot-and-Mouth Disease.

An atypical clinical variant of hand-foot-and-mouth disease (HFMD) with more extensive lesions and affecting adults has emerged during the past years, usually associated to the Coxsackievirus serotype A6 (CV-A6). We present a 19-year-old woman with a 3-day evolution eruption of papulovesicular lesions, which first appeared around the mouth and frontal area and rapidly spread. In addition, we present a 61-year-old man with a 4-day evolution asymptomatic eruption of papulovesicular lesions in both the hands and feet after suffering a cold 1 week before. Skin biopsies of both patients showed intraepidermal vesicles with spongiosis and ballooning, leading to reticular degeneration, apoptotic keratinocytes, and epidermal necrosis of the upper layers with neutrophil sloughing. Immunohistochemical studies for Coxsackie, Enterovirus, herpes virus, adenovirus, and measles were all negative. Cultures of blister fluid, reverse transcription polymerase chain reaction of skin biopsies, blood tests and serologies for exanthematic virus, and serum viral arrays were also negative. Only reverse transcription polymerase chain reaction of blister fluid confirmed Cocksakie A6. In conclusion, immunohistochemical studies with the commercially available viral antibodies do not seem to be useful in atypical HFMD cases. In these cases, to determine the typical histopathological features in HE is the fastest diagnostic aid.