Time of Onset of Selected Skin Lesions Associated with COVID-19: A Systematic Review

Introduction Distinct skin lesions associated with coronavirus disease 2019 (COVID-19) have been described, but data regarding their time of onset during the COVID-19 course are scant. Our objective was to systematically review the studies reporting the time of onset of selected skin lesions with respect to the reported onset of the COVID-19 core symptoms. Methods A comprehensive search of studies published before 21 January 2021 was performed on MEDLINE via PubMed database using a predefined strategy to identify relevant articles. Results Out of 354 references, 87 were selected, reporting a total of 895 patients with skin lesions associated with COVID-19. The most frequent pattern was exanthema (n = 430, 48%), followed by vascular (n = 299, 33%), urticarial (n = 105, 12%) and others (n = 66, 7%). Skin lesions occurred more frequently in the first 4 weeks from the COVID-19 onset (n = 831, 92%), whereas prodromal or late lesions were rarer (n = 69, 8%). The urticarial and exanthema patterns were more frequent in the first 2 weeks. About the vascular pattern some differences were noted among its subtypes. Livedoid lesions occurred mainly in the first 2 weeks, while chilblain-like lesions between weeks 2 and 4. Purpuric/petechial lesions were equally distributed during the first 4 weeks. Several skin manifestations did not fall into the pattern classification, including erythema multiforme, generalized pruritus, Kawasaki disease and others. Conclusion The diversity in the time of onset of skin lesions as well as their polymorphic nature likely reflects the diversity of the pathogenetic underlying mechanisms. PROSPERO database registration number CRD42021236331.