CNN —Actor Mandy Moore’s son recently woke up to a startling rash covering his body, according to her Instagram posts. Gianotti-Crosti syndrome. What is Gianotti-Crosti syndrome? Experts say they don’t know why some children get Gianotti-Crosti syndrome and others don’t, but it is thought to be a hypersensitive response to an underlying infection, according to the National Institutes of Health. Usually, the Gianotti-Crosti syndrome resolves itself over time — anywhere from a couple weeks to a couple of months, Levoska said.

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Persons: Mandy Moore’s, ” Moore, Melissa Levoska, Shari Lipner, Levoska, Epstein, Barr, “, ” Levoska, Lipner, Dermatologists, ”, it’s Organizations: CNN, Icahn School of Medicine, Weill Cornell Graduate School of Medical Sciences, National Institutes of Health, National Hospital Locations: Instagram, Mount Sinai, New York City, United States, Washington ,