Mixed diagnoses – 10 cases (8 of 11)

This is eczema herpeticum. There are characteristic clusters of umbilicated vesicles on the child's neck.

Eczema herpeticum is due to primary herpes simplex infection in a patient with atopic dermatitis, or rarely, Darier's disease or other conditions in which epidermal integrity is compromised. Eczema herpeticum can also complicate facial resurfacing by chemical peel or laser. In atopics, it can arise within the dermatitis or on normal-appearing skin.

The diagnosis can be confirmed by viral culture of blister fluid, obtained by deroofing a lesion and scraping it gently with a scalpel blade. More rapid confirmation can be obtained by immunofluorescent staining.

As eczema herpeticum can become extensive and severe, the patient should be promptly prescribed aciclovir. The dose depends on severity and ranges from 200 to 800mg five times daily for 5 days. Oral valaciclovir and famciclovir are also suitable, but not currently available in New Zealand. Intravenous aciclovir is recommended for particularly severe cases.

Topical care with cold compresses using saline, weak vinegar solution or potassium permanganate followed by emollient application can reduce discomfort and speed healing. Any involvement in and around the eye should be evaluated by an ophthalmologist.

The patient should be considered contagious until the crusts fall off, which can take several weeks.

Active atopic dermatitis can be treated concurrently with topical steroid and emollients according to severity. Secondary bacterial infection necessitates oral antistaphylococcal antibiotics.