'COVID Toes' might be the latest unusual sign that people are infected with the novel coronavirus

• "COVID Toes," purple and swollen toes that look like they've been frostbitten, may be the latest indication of coronavirus infection.
• The American Academy of Dermatology has received over 200 submissions of dermatological manifestations that healthcare providers are seeing in patients with COVID-19. More than half the submissions note these lesions.
• "My message to the public would be, if you develop these, talk to your healthcare provider," said Dr. Esther Freeman, a dermatologist and epidemiologist at Massachusetts General Hospital who is managing the registry.
• "In the absence of another reason to have these 'COVID toes,' you may want to consider testing," she added.
• Read live updates about the coronavirus here.

Purple and swollen toes that look like they've been frostbitten may be the latest indication of coronavirus infection, doctors say.

Dubbed 'COVID Toes' by the dermatology community, this symptom could be the latest indication that you should get tested for coronavirus. Others have included anosmia, or a loss of smell, and conjunctivitis, also known as pink eye, which the American Academy of Ophthalmology recently suggested could be a sign of the virus.

The American Academy of Dermatology (AAD) launched a registry last week to track the dermatological effects that COVID-19 virus patients may be experiencing and received over 200 submissions from healthcare providers as of Wednesday afternoon.

Dr. Esther Freeman, a dermatologist and epidemiologist at Massachusetts General Hospital and a faculty member at Harvard medical school, is managing the registry in collaboration with the AAD. So far, Freeman told Business Insider, around half of the cases in the registry note these lesions in the hands or feet that resemble frostbite.

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She's also seen several of these cases in her own patients in recent weeks. She said she connected with patients through virtual consultations.

"My message to the public would be, if you develop these, talk to your healthcare provider," Freeman said.

If you go to a doctor, they'll ask questions about whether there may be any other reasons why you would be developing these lesions.

"In the absence of another reason to have these 'COVID toes,' you may want to consider testing and think about potentially limiting the risk of spread to other people," she said.

What causes COVID toes?

A lot is unknown about what may be causing this condition, Freeman said. She said there are a few main theories circling in the medical community.

One of the theories is that the lesions may be due to the virus causing general inflammation in the body. Another is that the virus may be causing vasculitis, meaning the walls of the blood vessel themselves are becoming inflamed. A third possibility is that the lesions may be caused by blood clots in vessels in the skin. Doctors are increasingly seeing blood clots as a complication of the virus.

But it may end up that more than one of these hypotheses ends up being true, Freeman said. It could be a combination of these things or some patients may experience 'COVID toes' for one of these reasons while others may experience them for another.

"It's possible that it's a spectrum," she said.

Interest from the medical Twitter community

Dr. Ilan Schwartz, an infectious disease specialist in Edmonton, Alberta, recently posted a tweet about 'COVID Toes' that has garnered over 2,300 retweets and 3,500 likes on the site.

—Ilan Schwartz MD PhD (@GermHunterMD) April 14, 2020

Schwartz told Business Insider that though he hasn't yet seen COVID-19 patients with swollen toes in his own practice, what he has seen is immense interest from the medical community in the topic. He said he's had several people leave comments on his post and send him private messages relaying their own experiences with the symptoms.

In a recent webinar where Schwartz was presenting on the virus to family doctors in Calgary, Schwartz said that an audience member also raised the question of whether he or others had seen lesions in the toes of coronavirus patients.

Schwartz said that though it's still early and the cases are mostly anecdotal, he feels quite certain that the frostbite-like toes in some COVID-19 patients are a sign of the disease.

"But it's going to take a very large population that is surveyed to be able to make any definitive findings, and that might still take a while," he said.

Patients with COVID toes tend to be younger, and may not have other symptoms

Most COVID-19 patients experiencing painful and swollen toes seem to be younger, said Dr. Lindy Fox, a professor of dermatology at the University of California at San Francisco, who is also involved in the AAD's registry. Many of them also appear to be relatively healthy and show few or no other symptoms of COVID-19.

Fox suggests that anyone experiencing these symptoms be tested with both a test to see if they're currently infected, and an antibody test, which shows if they were infected previously. However, she notes that the inflamed and purple toes themselves aren't necessarily indicative that someone may develop other serious symptoms of the virus.

The toe problems can show up during or after the other coronavirus symptoms have subsided, Fox said.

COVID toes may reveal the scope of exposure to the coronavirus

These frostbite-like symptoms can happen for reasons unrelated to the coronavirus, especially during the winter or in areas with cold climates. However, the sheer number of cases of these toe problems, called pernio, that the medical community has seen, especially in countries like Spain and Italy that have warmer climates, has prompted doctors to consider the cases as related to the virus.

"It is an astonishing number" of patients who have these symptoms in their toes, said Fox.

She said that the lack of testing for the virus means we don't really know how many people have had it, and these toe problems are another indication that the virus is widespread.

"We're understanding that many more people than we ever thought were exposed to the virus, had it, because our testing has been so poor," Fox said.

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