Contact dermatitis sparing the eruption of herpes zoster and its periphery.

A 63-year-old male developed allergic contact dermatitis with antibiotic ointment applied to the skin eruptions of herpes zoster. From the result of patch test, fradiomycin sulfate contained in the ointment was identified as the contact sensitizing antigen. Strangely, this contact dermatitis was confined to the area surrounding the sores, sparing the lesions and their periphery. We postulated that a decrease in Langerhans cell activity in the herpes zoster lesions and their peripheral area was primarily responsible for this phenomenon, since an important role of Langerhans cells in host defence against herpes virus infection has recently been demonstrated.