A clinicopathological description of COVID-19-induced chilblains (COVID-toes) correlated with a published literature review.

BACKGROUND: The abundance of publications of COVID-19-induced chilblains has resulted in a confusing situation. METHODS: This is a prospective single-institution study from March 15 to May 13, 2020. Thirty-two patients received PCR nasopharyngeal swabs. Of these, 28 had a thoracic CT-Scan, 31 had blood and urine examinations, 24 had skin biopsies including immunohistochemical and direct immunofluorescence studies, and 4 patients had electron microscopy. RESULTS: COVID-19-induced chilblains are clinically and histopathologically identical to chilblains from other causes. Though intravascular thrombi are sometimes observed, no patient had a systemic coagulopathy or severe clinical course. The exhaustive clinical, radiological and laboratory work-up in this study ruled-out other primary and secondary causes. Electron microscopy revealed rare, probable viral particles whose core and spikes measured from 120-133 nm within endothelium and eccrine glands in 2 cases. CONCLUSION: This study provides further clinicopathologic evidence of COVID-19 related chilblains. Negative PCR and antibody tests do not rule-out infection. Chilblains represents a good prognosis, occurring later in the disease course. No systemic coagulopathy was identified in any patient. Patients presenting with acral lesions should be isolated, and chilblains should be distinguished from thrombotic lesions (livedo racemosa, retiform purpura or ischemic acral necrosis). This article is protected by copyright. All rights reserved.