Herpes Simplex Dermatitis

A 4-year-old boy presented with a pustular rash on the radial aspect of the right wrist. The rash appeared about 4 days earlier as a group of vesicles on an erythematous base. The lesions caused mild discomfort.

The child had had recurrent herpes labialis since early infancy. He had no history of herpes simplex virus (HSV) infection elsewhere. About a week before presentation, the child fell with his right hand outstretched onto broken glass. The erythema on the proximal index finger and the narrow linear abrasion distal to the pustules were remnants of that injury.

Grouped vesicles or pustules on an erythematous base are characteristic of herpes simplex dermatitis. This infection is usually caused by HSV type 1 (HSV-1) and can appear on any skin surface. Primary HSV-1 infection is often asymptomatic. Symptoms, when present, may include pain, headache, tender lymphadenopathy, fever, and malaise. The mild trauma to the right hand could have been a trigger for the eruption in this child. Fever also has been considered a possible trigger.

HSV-1 infections can be diagnosed clinically; however, an HSV culture or DNA test may be necessary for confirmation. In this case, culture of one of the pustules was positive for HSV-1, and the diagnosis was confirmed by direct immunofluorescence.

Most cases of HSV-1 infection are self-limited. The use of antiviral medications depends on the severity of the lesions. Typically, the earlier antiviral agents are started, the better the treatment response. After 2 or 3 days of the illness, the benefit of their use is questionable. For mild primary HSV-1 infection in children, antiviral agents are not used as first-line treatment; however, an antibiotic can be given because of the potential for secondary bacterial infection.

This patient was treated with mupirocin ointment, applied 4 times daily. The lesions resolved within 10 days. *