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Clinical images of patients with hives, swollen lips, chickenpox-like rashes, and red or purple lesions on the feet known as “covid toes,” have been published in medical studies since the start of the pandemic, demonstrating how the virus can affect the skin.

These images can help doctors diagnose patients who are otherwise asymptomatic – if they have light skin.

But images of darker-skinned patients have largely not been included in medical studies showing how COVID-19 can present on the skin, even as the disease has disproportionately affected people of colour in Canada and the United States. Symptoms can appear very differently on dark skin tones, underscoring the need for inclusion in clinical studies.

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The violaceous color of purpura is obvious on the left patient's light skin. In a patient with dark skin, purpura appears dark brown rather than violaceous, as seen at right.Image appears with permission from VisualDx

“Black folks in Canada, specifically Toronto, are overrepresented in terms of the burden of COVID-19,” said Bolu Ogunyemi, a dermatologist and clinical assistant professor of medicine at Memorial University in Newfoundland.

“So it’s unfortunate that we’re actually underrepresented in records of the manifestation from skin for this disease.”

The COVID-19 studies reflect a pattern in which darker skinned patients are largely missing from medical literature, part of an issue of racism within the medical system.

A literature review in The British Journal of Dermatology found that out of 36 studies showing images of COVID-19 presentations on skin published between December, 2019, to May, 2020, there were zero images of dark skin tones.

Researchers evaluated each clinical image using the six-point Fitzpatrick scale, which categorizes skin tones from lightest to darkest, and found that 92 per cent of the 130 images were of skin in the first three categories, which range from the lightest coloured skin to a medium tone. There were zero images of skin in the two darkest Fitzpatrick categories.

While it is not yet clear how significant these skin lesions can be in diagnosing COVID-19, understanding what they look like could lead to earlier testing. Some provinces, such as Nova Scotia, have added symptoms of red or purple fingers or toes to a list of symptoms that indicate a person should get tested.

“We’re still trying to figure out what these manifestations actually mean,” said the main author of the study, Jenna Lester, who is an assistant professor of dermatology at the University of California, San Francisco.

“But if there is a rash that patients can identify themselves when they were perhaps asymptomatic and can use it as a way to know they need to get tested but we’re not showing it in dark skin – it is a huge disservice to patients.”

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In dark skin, the inflammation of dermatomyositis is more subtle, has a brown to purple colour and does not look like typical inflammation. In light skin, the inflammation due to dermatomyositis is easily seen as red or pink skin.Image appears with permission from VisualDx

Including examples of what diseases can look like on dark skin is important because indicators such as redness may be difficult to spot on dark skin, said Lynn McKinley-Grant, associate professor of Dermatology at Howard University College of Medicine and president of the U.S.-based Skin of Color Society.

Redness on light skin can appear as a different shade on darker skin, she said, or not appear at all. Doctors may have to employ different diagnostic methods to determine the issue, such as using touch to see whether the skin is warm. Sometimes, darker skin can also react very differently.

“In the textbooks it’ll describe a rash as flat and not itchy, but in darker skin types, it’ll be raised and itchy, but still be in the same pattern,” Dr. McKinley-Grant said.

The Skin of Color Society has shared images on social media of darker skin showing symptoms that are similar in appearance to COVID-19 symptoms.

While most health care units in Canada do not yet collect race-based data on COVID-19 patients, statistics show that the most diverse geographic areas also have some of the highest rates COVID-19. In early June, after health care professionals across the country raised concerns about the lack of data on how COVID-19 has affected racialized populations, Ontario had granted some health units permission to begin collecting race-based data.

In the U.S., where race-based data are available, studies show that African-Americans are almost three times as likely to test positive for the virus than white people.

Some doctors in Canada have linked the lack of representation in COVID-19 studies to larger issues of representation in medical studies and textbooks, across all disciplines.

Edgar Akuffo-Addo, a first-year medical student at the University of Toronto, says he has experienced this first hand.

In a first-aid training course he recently completed, Mr. Akuffo-Addo said participants were instructed to check for signs of shock by pressing down on a patient’s fingernails and waiting to see how long it took to turn red again.

“I tried to do the test on myself, and I couldn’t see it on my own skin,” he said. In addition, he said all the patients featured in the video training materials were white.

Mr. Akuffo-Addo describes the lack of representation as “troubling and worrying” and has embarked on his own review of clinical images of skin conditions related to COVID-19, and has so far examined 1,000 images in studies from Spain, France, Italy, the U.S. and Canada. Mr. Akuffo-Addo said that he confirmed with the authors of those studies that all patients were white.

Dr. Ogunyemi said the study of dermatology has been historically white.

When the field was first developing in Britain, the U.S. and Canada, he said, there was a smaller proportion of people of colour, so the criteria for the diagnosis of skin issues was centred around people with lighter skin. But these criteria have not changed significantly since that time.

“The problem is our population in these countries is changing – but the definition of skin disease is not keeping up with the pace.”

Studies also show that a mistrust of the medical system is a major reason why people of colour may choose not to participate in medical studies, stemming from a history of mistreatment as well as discrimination within the medical system.

Dr. Ogunyemi said that because the information on treating dark skin may not be readily available, Canadian doctors may have to take additional steps to ensure they are comfortable and able to treat people with dark skin.

“I think like a lot of things, you have to take a conscious effort, you have to go out of your way.”

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