Focus on “COVID Toes”

Worldwide case collections of cutaneous manifestations of coronavirus disease 2019 (COVID-19) are ongoing, with acral lesions (similar to classic chilblains) being one of the reported patterns. Also known as pernio-like, pseudo-chilblain, acute acro-ischemia, and “COVID toes,” the pattern of acral lesions is described as erythematous to purple purpuric macules, papules, and/or vesicles. Its close temporal appearance with the COVID-19 pandemic suggests that the two are associated. Galván Casas et al¹ confirmed that 29 of 71 cases of pseudo-chilblains were associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), noting that this pattern is less commonly associated with virologic confirmation. Fernandez-Nieto et al² reported that 95 of 132 patients with acro-ischemic changes had a chilblains pattern. Acral lesions often occurred later during the course of COVID-19, and late-stage disease testing was believed to partly account for low positive rates of SARS-CoV-2 infection (2 of 11 patients).

Two case series in this issue question a direct association between COVID-19 and acral lesions. Herman et al³ examined 31 patients with acral lesions and found a relatively low mean body mass index (22, calculated as weight in kilograms divided by height in meters squared), a known predisposing factor for perniosis. None of the patients tested positive for COVID-19 by nasopharyngeal swab and reverse transcriptase–polymerase chain reaction (RT-PCR) for SARS-CoV-2, nor were SARS-CoV-2–specific immunoglobulin (Ig) M or IgG antibodies detected. Roca-Ginés et al⁴ evaluated 20 children and adolescents with acral purpuric changes. No patient had COVID-19 symptoms or evidence of infection according to results of nasopharyngeal swab and RT-PCR or viral serologic testing. In both studies, extensive testing failed to identify other risk factors for these acral lesions, and a subset of patients had biopsy results consistent with perniosis. Both author groups propose that lifestyle changes imposed by the quarantine, such as walking barefoot in unheated homes, inactivity, and time spent in sedentary positions, could explain these findings.

It is still unclear whether a viral cytopathic process vs a viral reaction pattern or other mechanism is responsible for “COVID toes.” Further complicating matters is the lack of confirmatory SARS-CoV-2 testing in some cases, which instead rely on indirect evidence such as systemic symptoms consistent with possible infection, cohabitation with an individual with COVID-19, or serologic test results pointing to the convalescent phase of infection. Conflicting evidence highlights that testing needs to occur in larger numbers and also at different stages of the disease to determine if a low viral load, undetectable with current methods, or the inability to mount an adequate immune response accounts for the negative SARS-CoV-2 test results. Dermatologists must be aware of the protean cutaneous findings that are possibly associated with COVID-19, even if our understanding of their origins remains incomplete.

Published Online: June 25, 2020. doi:10.1001/jamadermatol.2020.2062

Corresponding Author: Claudia Hernandez, MD, 1653 W Congress Pkwy, 220 Annex, Chicago, IL 60612 (cherna7jama@gmail.com).

Conflict of Interest Disclosures: None reported.