Mandy Moore says her toddler has a rare skin condition called Gianotti Crosti syndrome

Actress Mandy Moore has revealed that her 2-year-old son August, nicknamed Gus, has been diagnosed with a rare skin condition called Gianotti Crosti syndrome.

Moore took to social media on Friday to describe a "crazy rash" Gus woke up with last week.

"We thought maybe an eczema flare? Poison Oak? Allergy," she wrote on Instagram Stories. "We tried to deduce what it could be and did anything to help him find relief from the itch."