Coronavirus infection-induced chilblains11Kolivras A, Dehavay F, Delplace D, et al. Coronavirus (COVID-19) infection-induced chilblains: A case report with histopathologic findings [published online ahead of print, 2020 Apr 18]. JAAD Case Rep. 2020;6(6):489‐492.:

A mechanism has recently been considered to explain the appearance of autoimmune phenomena following the whole SARS-CoV2 infection: molecular mimicry22Cappello F Is. COVID-19 a proteiform disease inducing also molecular mimicry phenomena? Cell Stress Chaperones 2020 May;25(3):381–2. https://doi.org/10. 1007/s12192-020-01112-1.^,33Sedaghat Z, Karimi N. Guillain Barre syndrome associated with COVID-19 infection: A case report. J Clin Neurosci 2020 Apr 15. https://doi.org/10.1016/j.jocn.2020. 04.062. pii: S0967-5868(20)30882-1.^,44Cappello F. COVID-19 and molecular mimicry: The Columbus’ egg? J Clin Neurosci 2020 May 6. https://doi.org/10.1016/j.jocn.2020.05.015. pii: S0967-5868(20) 31156-5. Lucchesi and Floel55Lucchese G, Flöel A. Molecular mimicry between SARS-CoV-2 and respiratory pacemaker neurons. Autoimmun Rev 2020 May 1:102556https://doi.org/10.1016/j. autrev.2020.102556 have hypothesized a molecular mimicry mechanism between neuronal proteins present in the brain stem respiratory pacemaker neurons (DAB1, AIFM and SURF1) and viral epitopes of SARS-CoV2 treated antigenic. The same mechanism according to Angileri et al. could be responsible for anosmia, leukopenia and multi-organ failure caused by vascular damage, assuming they are associated with the molecular mimicry 66Angileri F. Molecular mimicry may explain multi-organ damage in COVID-19 Autoimmunity Reviews 2020 May 18 https://doi.org/10.1016/j.autrev.2020.102591.. A type 3 hypersensitivity therefore occurs with the deposition of antibody antigen complexes precipitate inside the tissues, in particular the blood vessels, inducing a serious inflammatory state by the action of the complement anaphylatoxins (C3a and C5a), which in turn stimulate the release of histamine from mast cells and the recruitment of phagocytes, first in neutrophils, the main cause of tissue damage and following «leukocytoclastic vasculitis» (LCV), also reported in the English medical literature from the term «hypersensitivity vasculitis77C.A. Janeway Jr., P. Travers, M. Walport, M. Shlomchik, Immunobiology: the immune system in health and disease, fifth ed., Garland Science, New York, 2001^,88D. Baigrie, P. Bansal, A. Goyal, J.S. Crane, Leukocytoclastic vasculitis (hypersensitivity vasculitis), StatPearls Publishing, Treasure Island, 2020». This pathogenic mechanisms could explain the appearance of chilblain-like lesions due to SARS COV-2 infection. In conclusion we think there is a correlation between chilblain like lesion and SARS-Cov2 infection, but further studies are needed to prove it. We hypothesize this for an increased number of this skin lesions described in the literature during this period, as in our experience, and also because such lesions appeared at a time when temperatures were mild in Southern Italy and patients were at home because of the lockdown. To our knowledge, this is one of the few studies that collects a series of patients with chilblain like lesions, evaluating the possible association with COVID 19 (oropharyngeal swab and serology test) but also for rheumatological diseases. Many questions remain open about interaction host-virus.

ACKNOWLEDGMENTS : Thanks to Italian Federation of Pediatrician (FIMP) of Messina for collaboration.

IMPACT STATEMENT

During the outbreak of COVID-19 many chilblain-like lesions are being increasingly reported.The increase in the number of cases of chilblain-like lesions compared to the cases with which we come into contact in our clinical practice every year, in association with the mild temperatures observed in those months in Southern Italy and the concomitant lockdown, led us to hypothesize a possible correlation with SARS Cov 2 infection. To our knowledge, this is one of the few studies that collects a series of patients with chilblain like lesions, evaluating the possible association with COVID 19 (oropharyngeal swab and serology test) but also for rheumatological diseases.

REFERENCES