A 4-month-old girl was brought to our clinic with a 4-week history of blisters on her arms and legs. The eruption started on her right posterior and lateral calf and then appeared on her left calf and bilateral elbows. Other than the blisters, the girl appeared well and was eating and growing normally. Her parents said she had not been in contact with anyone with a similar rash or itching. They also denied recent outdoor activities, camping trips, or environmental exposures.
The child had been previously treated with topical and oral steroids and oral antibiotics by a pediatrician, but the rash barely improved. On physical examination, she was afebrile with well-demarcated erythematous papules and plaques with bullae, and erosions with honey-colored crusts. The rash was distributed symmetrically on the bilateral posterior and lateral lower legs and lateral upper arms (FIGURE).