Mandy Moore’s son was diagnosed with Gianotti-Crosti syndrome. Here’s what that means

Actress Mandy Moore's son was diagnosed with Gianotti-Crosti syndrome.

Actor Mandy Moore’s son recently woke up to a startling rash covering his body, according to her Instagram posts.

It took trips to urgent care, the pediatrician, a dermatologist and a pediatric dermatologist to figure out what was causing him to itch all over his arms, legs and feet. The cause? Gianotti-Crosti syndrome.

“This parenting thing is weird and hard and sometimes you feel so helpless,” Moore wrote on Instagram on July 28. “As long as he is smiling through it, we are a-okay.”

The skin disease is a rare condition, and it makes sense that it would be difficult for many doctors to identify, said dermatologist Dr. Melissa Levoska, an assistant professor of dermatology at the Icahn School of Medicine at Mount Sinai in New York City.

Here is what you need to know about the disease.

Gianotti-Crosti syndrome is a benign rash that usually occurs on the face, buttocks, arms and legs but usually doesn’t involve the scalp, chest or back, said Dr. Shari Lipner, associate professor of clinical dermatology at Weill Cornell Graduate School of Medical Sciences in New York City.

The rash is characterized by hard pink bumps that can often be itchy, she added. Those bumps are usually flat at the top, Levoska said.