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

Le Cleach, L.; Dousset, L.; Assier, H.; Fourati, S.; Barbarot, S.; Boulard, C.; Bourseau Quetier, C.; Cambon, L.; Cazanave, C.; Colin, A.; Kostrzewa, E.; Lesort, C.; Levy Roy, A.; Lombart, F.; Marco‐Bonnet, J.; Monfort, J.B.; Samimi, M.; Tardieu, M.; Wolkenstein, P.; Sbidian, E.; Beylot‐Barry, M.

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.