Dermatology — Eczema Herpeticum Disseminated HSV in Atopic Dermatitis

A 6-year-old child with a 2-year history of atopic dermatitis presents with sudden onset of fever (39.2°C), malaise, and a new eruption over the face and neck. Examination reveals the lesions marked **D** in the diagram — monomorphic punched-out erosions with hemorrhagic crusts of uniform size distributed over areas of preexisting eczema. The child's mother reports exposure to a relative with active herpes labialis 8 days ago. Which of the following is the MOST appropriate immediate management?