One of the first to report “purple toes” was American dermatologists, who found that 55% of patients had a specific lesion of the skin of the toes, similar to frostbite, as the only symptom. As a rule, in such cases, irritation of a bright red color appears, which later acquires a purple tint. Sometimes this condition is accompanied by painful sensations in the fingers, itching and blisters appear.
The experts noted that in four patients in the sample, these symptoms appeared before they confirmed the coronavirus, in another 14 people they developed after receiving a positive PCR test.
In a new study, researchers from the University of Paris in France focused on studying the mechanism that causes damage to the skin of the toes after infection with the coronavirus. They recruited 50 patients who had this symptom, and the control group included 13 people with similar skin lesions that were caused by frostbite and not associated with infection for comparison.
Scientists conducted a study of the antibodies and blood biomarkers produced associated with endothelial dysfunction, as well as a series of skin tests on all participants. It turned out that the “purple fingers” are a “side effect” of the immune response to the invasion of the virus.
According to scientists, in some cases, the body begins to generate an immune response with a high level of certain autoantibodies, which begin to attack not only the virus, but also its own cells and tissues, mistaking them for foreign ones. This mechanism also involves type 1 interferon, a key protein involved in the fight against the pathogen. Specific damage to the skin is caused by cells lining the small blood vessels associated with the affected area.
Podiatrist from the UK Ivan Bristow (Ivan Bristow) said that in most patients with COVID-19, these lesions usually go away on their own without additional intervention, reports the BBC. In severe cases, treatment with creams and other means may be required.