Visual Diagnosis: 7-year-old Girl with a Facial Rash

Presentation

A previously healthy, fully immunized 7-year-old girl presents to the dermatology clinic for evaluation of a rash on her left eyelid, forehead, and scalp. Her symptoms started 1 week earlier, first with pain of the left eyelid and subsequently, 2 days later, with scattered red papules around her left eye. She was evaluated by her pediatrician and treated with prednisolone for presumed allergic contact dermatitis to poison ivy. The rash evolved into vesicles distributed on the left eyelid and then spread to her forehead and scalp, prompting an emergency department visit. She was diagnosed as having cellulitis and was treated with oral clindamycin. Despite this therapy, she developed progressive edema of her left eyelid associated with eyelid pain. Her pediatrician urgently referred her to an ophthalmologist, who notes significant left periorbital edema but otherwise normal ophthalmic examination findings, including normal visual acuity and normal corneal examination without evidence of keratitis or ulceration. She is referred to a dermatologist on the same day, 9 days after her initial symptoms developed.

The patient has no fevers, nasal congestion, sore throat, cough, vomiting, diarrhea, headaches, or changes in mental status. The rash is associated with pruritus. She has not taken any new medications other than the antibiotics and corticosteroids prescribed for this eruption, and she has had no exposures to plants, new foods, or toxins. She has no known sick contacts. She has no significant medical history, and her immunizations are up to date.

On physical examination, she …