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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323324/
The pathogenesis of the half‐moon‐shaped transversal red bands seen in our patient after SARS‐CoV‐2 infection is unknown. A localized microvascular injury secondary to inflammatory immune response and a procoagulant state 7 might play a central role. Due to the localization, we hypothesized a damage of the capillary network of the distal subungual arcade.
To the best of our knowledge, this is the first case of nail involvement. This sign is peculiar and has not been previously described even in dermatological or systemic diseases. Further studies are needed to validate our finding and to assess whether red half‐moon nail could represent a pathognomic sign of COVID19.
