"COVID toes": a meta-analysis of case and observational studies on clinical, histopathological and laboratory findings.

Background: Coronavirus disease (COVID-19) is related to several extrapulmonary disorders; however, little is known about the clinical, laboratory and histopathological characteristics of pernio-like skin lesions associated with COVID-19 infection. Objective: To evaluate and summarize the clinical, laboratory and histopathological characteristics of pernio-like lesions reported in the literature. Methods: We conducted a search of the PubMed, SciELO and ScienceDirect databases for articles published between 1 January 2020 and 30 November 2020, following the PRISMA recommendations (PROSPERO registration ID: CRD42020225055). The target population was individuals with suspected or laboratory-confirmed COVID-19 with pernio-like lesions. Observational studies, research letters and case/series reports were all eligible for inclusion. Observational studies were evaluated using a random-effects model to calculate the weighted mean prevalence, overall mean and 95% confidence interval. We evaluated case studies using the chi-square test for dichotomous variables and the Mann-Whitney test for continuous variables. Results: A total of 187 patients from case reports and 715 patients from 18 observational studies were included. The mean age of patients was 16.6 (14.5–18.8) years. Feet were affected in 91.4% (87.0–94.4%) of patients in observational studies. The proportion of patients with a positive RT-PCR test was less than 15%. Lesion topography and morphology were associated with age. Conclusion: Lesions mostly occurred in pediatric patients, and the morphological characteristics tended to differ between pediatric and non-pediatric populations. There is a possible multifactorial component in lesion pathophysiology. The non-positivity of laboratory tests does not exclude an association with COVID-19. Chilblain-like lesions may be a late manifestation of COVID-19.