Evolution of incidence of chilblain-like lesions in children during the first year of COVID-19 pandemic

Background: The COVID-19 pandemic has brought innumerable reports of chilblains. The relation between pernio-like acral eruptions and COVID-19 has not been fully elucidated because most reported cases have occurred in patients with negative microbiological tests for SARS-CoV-2.

Methods: A retrospective study of 49 cases of chilblains seen during the first year of the pandemic in a children's hospital in Madrid, Spain. The incidence of these skin lesions was correlated with the number of COVID-19 admissions and environmental temperatures. Patients were separated into two groups depending on the day of onset (strict lockdown period vs. outside the lockdown period).

Results: Most chilblains cases presented during the first and third waves of the pandemic, paralleling the number of COVID-19 admissions. The first wave coincided with a strict lockdown, and the third wave coincided with the lowest ambient seasonal temperatures of the year. Systemic symptoms preceding chilblains were more frequent in the first wave (45.8% vs. 8.0%, p = .002), as was the co-occurrence with erythema multiforme-like lesions (16.7% vs. 0%, p = .033). Laboratory test and skin biopsies were performed more frequently in the first wave (75.0% vs. 12.0%, p < .001; and 25.0% vs. 0%, p = .007; respectively). Five patients developed recurrent cutaneous symptoms.

Conclusions: An increased incidence of chilblains coincided not only with the two major waves of the pandemic, but also with the strict lockdown period in the first wave and low seasonal temperatures during the third wave. Both increased sedentary behaviors and cold environmental temperatures may have played an additive role in the development of COVID-19-related chilblains.