1. Service de Pédiatrie, Hospices Civils de Lyon, Lyon, France
2. Department of Dermatology, INSERM U 905, University of Rouen, Rouen, France
3. Service de Dermatologie, Hôpital Necker, Paris, France
4. Service de Dermatologie, Hospices Civils de Lyon, Lyon, France
5. Université de Saint‐Etienne, St Etienne, France