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Chilblains, also known in medical parlance as “perniosis” are a disorder associated with cold and dampness typical of acral skin (i.e. distant areas of the body). With the improvement of socio-sanitary conditions, its presence has been associated with northern European areas, cold climate or season and absence of heating.

To diagnose it, it is only necessary to recognize it visually, it does not require a biopsy or blood tests (although we can consider complementary tests in case of doubt with other processes).
How does it manifest itself? First, the characteristic location, such as fingers, toes, nose or ears. We can see red to purplish coloration and it is often associated with swelling (edema), induration (the skin feels hard, as if there were “something” underneath) and even blisters or ulcers.

Why is it interesting to comment on this process, at this time (it is nothing new)? What is topical is any knowledge of COVID infection. As you may have heard, it has been associated with skin lesions, among many other manifestations. These lesions are heterogeneous, varied in appearance, and appear at different times throughout the course of evolution…Thanks to the efforts and observation of physicians and dermatologists who have treated these patients, several patterns have been described; one of them, very characteristically associated with COVID, is acral perniosiform.

I highly recommend the article Cutaneous manifestations in the context of SARS-CoV-2 infection (COVID-19), written by JM Carrascosa and collaborators and published in May last year in the journal Actas Dermo-Sifiliograficas (the text can be accessed freely by clicking on this link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458046/pdf/main.pdf

Also the article Classification of the cutaneous manifestations of COVID-19: a rapid prospective nationwide consensus study in Spain with 375 cases, by Galván-Casas and published in an important international Dermatology journal (British Journal of Dermatology, in 2020). You can also access the full article here: https://onlinelibrary.wiley.com/doi/epdf/10.1111/bjd.19163

It describes the “epidemic” of this type of lesions and how they were gradually associated with cases with respiratory symptoms, confirmed cases of COVID or with affected relatives. This, together with the fact that they occurred in months that were not particularly cold, led to the belief that this was a manifestation of the virus. It is important to note that they usually occurred in young patients, late and in the context of a disease with few symptoms. It should be taken into account that since it is a late manifestation, it is less likely to be accompanied by microbiological confirmation, which may “mislead” when attributing it to COVID.

Finally, to show you the richness and complexity of our specialty, I will comment that there are other disorders that may look like chilblains but are not; and that sometimes chilblains or perniosiform lesions may be markers of an internal disease (a hematological disease, for example). If you want to go deeper into the subject I recommend a very complete and updated review in this link: https://econtent.hogrefe.com/doi/pdf/10.1024/0301-1526/a000838

Dr. Beatriz Fleta