Most chilblains observed during the COVID-19 outbreak occur in patients who are negative for COVID-19 on PCR and serology testing.

Introduction Acral lesions, mainly chilblains, are the most frequently reported cutaneous lesions associated with COVID-19. In more than 80% of tested patients, nasopharyngeal swabs were negative on RT-PCR for SARS-CoV-2 when performed, and serology was generally not performed. Materials and methods A national survey was launched on March 30, 2020 by the French society of dermatology asking physicians to report cases of skin manifestations in patients with suspected or confirmed COVID-19 by using a standardized questionnaire. We report the results for acral manifestations. Results We collected 311 cases of acral manifestations (58.5% females, median age 25.7 years [range 18-39]). The most frequent clinical presentation (65%) was typical chilblains. In total, 93 cases (30%) showed clinical suspicion of COVID-19, 67 (22%) had only less specific infectious symptoms, and 151 (49%) had no clinical signs preceding or during the course of acral lesions. Histology of skin biopsies was consistent with chilblains (n= 26/29). Twelve patients showed significant immunological abnormalities. Ten patients were positive among the 150 (48%) who were tested (RT-PCR and/or serology). Seven of 121 RT-PCR-tested patients were positive and 5 of 75 serology-tested patients were positive (IgG) among them RT-PCR and serology were both positive for two patients. Seven of 121 RT-PCR-tested patients were positive for SARS-CoV-2 (6%), and 5 of 75 serology-tested patients had IgG anti- SARS-CoV-2 (7 %). Tested and untested patients or those with and without confirmed COVID-19 did not differ in age, sex, history or acral-lesion clinical characteristics. Conclusion The results of this survey do not rule out that SARS-CoV-2 could be directly responsible for some cases of chilblains but found no evidence of SARS-CoV-2 infection in large majority of patients with acral lesions during the COVID-19 lockdown period in France.