The news initially came from a press release shared on April 9 by the General Council of Official Colleges of Podiatrists in Spain after podiatrists began "registering numerous cases of sick people, mainly children and young people, who had small dermatological lesions on their feet"—sometimes in the absence of other COVID-19 symptoms; sometimes before the appearance of other symptoms. Those lesions, per the council, are "purple-colored" and typically appear around the tips of the toes, though they usually heal without leaving marks on the skin. The council compared the marks to those that result from chickenpox, measles, or pernio (small lesions that appear after exposure to very cold temperatures).

Image zoom Kristin Samuelson - Northwestern University

In April, International Federation of Podiatrists published a case study detailing similar findings, describing a 13-year-old boy who suddenly presented with lesions on both feet. Two days later, he presented with general COVID-19 symptoms—fever, muscle pain, and headaches—along with “intense itching and burning on the foot lesions.” The boy was never tested for COVID-19, nor were any other family members, but his sister and mother showed symptoms of coronavirus before the boy's symptoms showed up. The boy's foot lesions began to clear up within a week, per the report. The American Academy of Dermatology even has its own registry of dermatological issues possibly linked with COVID-19–including "COVID toes"—to better understand the link.

Recently, though, a small pair of studies called into question whether such lesions are symptom of the virus at all.

A research team in Belgium, reporting in JAMA Dermatology, described 31 mostly teenage and young adult patients with purplish-red lesions on their toes and/or fingers. None tested positive for the SARS-CoV-2 virus, which causes the illness, and all were negative for antibodies to the virus. Researchers suspect that these patients' skin symptoms may be due to community containment and lockdown measures imposed as a result of the pandemic. A majority (64%) reported decreased physical activity and more time spent in sedentary positions as they worked from home or were home schooled. Notably, most patients indicated that they remained barefoot or in socks most of the day.

Similarly, researchers in Spain evaluated 20 children and teens who developed a purplish skin rash on their feet and/or hands. None had COVID-19 symptoms or evidence of infection based on nasal swab and blood testing. Writing in JAMA Dermatology, the authors say one possibility is that the kids' symptoms may have been related to the quarantine experience of going barefoot or only wearing socks and engaging in little physical activity.

Of course, much remains unknown. Larger, well-designed studies involving control groups are needed to sort out any possible correlation between these toe lesions and coronavirus infections.

In April, International Federation of Podiatrists published a case study detailing similar findings, describing a 13-year-old boy who suddenly presented with lesions on both feet. Two days later, he presented with general COVID-19 symptoms—fever, muscle pain, and headaches—along with “intense itching and burning on the foot lesions.” The boy was never tested for COVID-19, nor were any other family members, but his sister and mother showed symptoms of coronavirus before the boy's symptoms showed up. The boy's foot lesions began to clear up within a week, per the report. The American Academy of Dermatology even has its own registry of dermatological issues possibly linked with COVID-19–including "COVID toes"—to better understand the link.

While it's unclear exactly why this may be happening with COVID-19 patients, Nazanin Saedi, MD, board-certified dermatologist at Thomas Jefferson University, says it may have something to do with how the virus stimulates inflammation. "It can be a localized inflammation to the finger or toes. Or, it can be the inflammation causing microclots in the circulation,” she says. She also points out that an increase in blood clotting has been seen in those who are very ill. “They see this in asymptomatic patients but also patients who are critically ill," says Dr. Saedi.

In a news release from Northwestern Medicine, dermatologist Amy Paller, MD, also noted that the reaction could be an immune response, likening it again to pernio. "Pernio, which this resembles but is a response to cold, involves clamping down of these small blood vessels —and we think something like this may be happening in response to the inflammation, perhaps caused as part of the response to the COVID-19 virus," she said.

Ted Lain, MD, board-certified dermatologist and chief medical officer at Sanova Dermatology agrees, adding that it may also be related to an immune-system reaction to the COVID-19 infection. “A particular immune system reaction...[that] may develop quickly in response to COVID-19 and cause these strange findings,” he explains.

Dr. Lain and Dr. Saedi add that the appearance of "COVID toes" mainly in children and young adults may signal that it's an immune response, too. "Children and young adults have stronger immune systems and they have a strong local response," says Dr. Saedi. Dr. Lain adds that "the scientific community hypothesizes that 'COVID toes' are possibly a sign of a robust immune response, and also could be why younger people tend to have a more mild course of infection than adults."

Right now, it's not totally clear whether the foot lesions are definitely related to COVID-19, "but when it's so common right now during a pandemic and is occurring in otherwise asymptomatic or mildly affected patients, it seems too much of a coincidence not to be a manifestation of the virus for patients in their teens and 20s," said Dr. Paller. The General Council of Official Colleges of Podiatrists in Spain echoed that statement, saying that "[it] urges its Colleges and its members to be very vigilant because this may be a sign of COVID-19 detection that can help to avoid the spread."

Ultimately, according to Dr. Saedi, "COVID toes" are still a bit of question mark. “Like with all aspects of this virus, there is so much to learn,” she says, but that dermatologists and patients alike should be aware of the potential symptom. As usual, if you notice this new symptom, or any other COVID-19-related symptoms, it's best to call your doctor regarding next steps for diagnosis and treatment.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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