Are 'covid toes' a real symptom of the coronavirus?

A frostbite-like rash on a person's toes might be a symptom of the new coronavirus, according to anecdotal evidence from dermatologists around the world. 

However, research is needed to determine whether this peculiar rash is truly caused by  COVID-19.

The pinkish-reddish rash can turn purple over time, and causes a burning sensation in some people, Dr. Esther Freeman, a dermatologist at Massachusetts General Hospital in Boston, told The Washington Post. But the inflammation tends to disappear without treatment in two to three weeks, Freeman said.

Related: 13 coronavirus myths busted by science 

So far, data shows that most people with so-called "covid toes" are asymptomatic or have mild cases of the disease, Freeman told the Post. Moreover, this strange rash tends to affect the younger crowd, including children and adults in their 20s or 30s, she said. 

"Most of the patients were young, healthy and had a benign clinical course," she told the Post. "I don't want people to think if they are having purple spots on their toes that they are going to end up on a ventilator in the ICU. That is not what we are seeing in the data."

A series of images of covid toes, photographed by Italian dermatologist Andrea Bassi and posted on Twitter show the range of appearances this rash can take.

But there is still much to learn, so Freeman and colleagues who are part of an American Academy of Dermatology task force created an online COVID-19 dermatology registry, where health care workers can report skin-related issues that seem to be linked to COVID-19, including the frostbite-like toe rashes. 

The researchers hope that the database will help doctors "understand the relationship between the virus and skin" and determine whether any of these skin problems can help with early disease detection, the team wrote in a report in the Journal of the American Academy of Dermatology.

So far, roughly half of the more than 300 database entries include covid toes, USA Today reported on April 27. 

Freeman noted that these toe rashes include skin sores or bumps known as pernio or chilblains, which usually occur when a person's foot has been exposed to extremely cold temperatures. However, because these rashes are happening in spring and in COVID-19 patients, cold temperatures are unlikely to be the cause.

Instead, dermatologists say it's possible that inflammation in the toes is causing the rash, Freeman told USA Today. Other ideas are that small blood clots in the toe's blood vessels may lead to the rash, or that the blood vessel walls are inflamed due to a condition known as vasculitis. 

One of the first mentions of covid toes appeared in early April, when French doctors noted that the rash had an "appearance of pseudo-frostbite" and "persistent, sometimes painful redness, and transient hive lesions." (Translated with Google Translate.)

Mention of the toes surfaced again on April 18 in a Journal of the American Academy of Dermatology case report. In the case report, the researchers described a 23-year-old student in Belgium who had "COVID-19 infection–induced chilblains." 

It's not uncommon for viruses to cause rashes. Measles, for instance, can cause itchy flat spots, while coxsackie can lead to painful sores in the hands, feet and mouth, the Post reported.

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Originally published on Live Science.

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