Many Moore’s Son Has Gianotti Crosti Syndrome, Here’s What This Rare Skin Condition Is

Here’s a rash diagnosis. On July 28, singer, songwriter, and actress Mandy Moore shared an Instagram Story about her and Taylor Goldsmith’s two-year-old son Gus being diagnosed with Gianotti-Crosti Syndrome (GCS). Now, that name may sound like an item on some kind of menu. But it’s actually something that you wouldn’t want to order for anyone.

Moore provided more backstory by writing, “This sweet boy woke up with a crazy rash on Saturday am,” on the post alongside a photo of Gus. She added, “We tried to deduce what it could be and did anything to help him find relief from the itch.” That meant that while everyone else in the U.S. was celebrating National Hammock Day on July 22, Moore was busy bringing her son to different doctors.

Eventually, doctors told Moore that the cause was “a viral childhood rash that just spontaneously appears called Gianotti-Crosti syndrome.” She described the rash as being “all over his legs and feet [ouch] and the backs of his arms but nowhere else.”

The following E News segment showed more of Moore’s Instagram story as well as photos of her son’s rash:

GCS is otherwise known as “papular acrodermatitis of childhood” and “papulovesicular acrolated syndrome” because medicine often offers different ways to say the same thing. GCS can happen when you’ve gone viral—but not in a social media kind of way. It is thought to be your body reacting in a hypersensitive way to some kind of viral infection. And in this case, hypersensitive means reacting by breaking out into a rash and potentially fevers and enlarged lymph nodes and not emotionally as in, “That virus is so mean.”

A range of different viruses may prompt such a reaction. The most common culprit is the Epstein-Barr virus. But GSC can be seen with the Hepatitis A, B, or C virus, cytomegalovirus, enterovirus, coxsackievirus, rotavirus, adenovirus, human herpes virus-6, respiratory syncytial virus, parvovirus B10, rubella, HIV, or parainfluenza. In some cases, GCS may appear after getting vaccinated against polio, hepatitis A, diphtheria, small pox, pertussis or influenza.

This condition tends to affect children from ages one to three years. So if you are in this age group and reading this, congratulations on your ability to read. If you are older, you may not be out of the woods quite yet when it comes to the risk of GCS. This syndrome has been seen in kids as young as three months to as old as 15 years of age. It is more common in kids with atopic dermatitis, otherwise known as eczema.

GCS can be quite a bumpy ride, so to speak. The word “papular” means “bump” is dermatology-speak. Each GCS lesion is a one-to-10 centimeter symmetric bump that has a red-to-pink-to-brown color. The word “vesicular” means “fluid-filled.” Thus these bumps may have fluid inside them.

The bottom line is that these bumps typically will first appear in the same part of the body: your buttocks, otherwise known as your butt cheeks, your derrière, or caboose. These bumps may eventually spread to other parts of your body such as your face, arms, and legs. Ah, but (or butt), these lesions don’t go everywhere. Interestingly, your chest, back, belly, palms and soles will likely be spared.

Over time, these bumps can coalesce together to form larger lesions. As Moore indicated, this rash can get quite itchy. These lesions can last anywhere from 10 days to several weeks. All told this condition can last from four to eight weeks.

There is no magical test or app that tells you that you have GCS. A doctor will base his or her diagnosis on a combination your history, the appearance of the rash, and the lack of evidence that something else in going on with your skin. A skin biopsy is not necessary unless you want to rule out other conditions.

There also is no magical treatment for GCS either. There is basically no treatment, magical or otherwise. The main thing that you can do is use medications like antihistamines to handle the itchiness. Alleviating the itchiness can help prevent scratching which could lead to that part of the skin being infected with bacteria. But nothing will really shorten the course of the condition.

Fortunately, there are no real long term consequences of having GCS by itself. Sure, it may affect dates and job interviews. But at age two, those would be of less concern. Expect Moore’s son to make a full recovery from GCS after suffering some of the bumps of being a two-year-old for several weeks.