Dermatologic manifestations of coronavirus disease 2019 (COVID-19)

Abstract

The cutaneous manifestations associated with coronavirus disease 2019 (COVID-19) are frequent and varied. Knowing these manifestations facilitates the diagnosis of asymptomatic or mildly symptomatic cases, contributing to reduce the spread of the virus. There are 5 main presentation patterns: acral areas of erythema-oedema with vesicles or pustules (pseudo-perniosis), other vesicular eruptions, urticarial lesions, maculopapular eruptions and livedo or necrosis. Most patterns can be further subdivided. The prognosis depends on the age of the patient and the severity of the respiratory clinic, not on the skin manifestation itself. Pseudo-chilblain lesions and vesicular eruptions are considered suggestive of COVID-19, while the rest of manifestations are unspecific and could occur in the context of other diseases. The physiopathological mechanisms involved in the appearance of skin lesions have yet to be categorized. There are 3 main hypotheses: hyperactive immune response, activation of the complement pathway and alterations in the coagulation cascade. Different alterations in each pathway would justify the great variety in the way that the different skin manifestations are presented. The causal relationship between some of the skin manifestations and COVID-19 is not yet fully demonstrated, since there are other factors such as drugs or fever that could be confounding factors. The presence of viral particles has been demonstrated by immunohistochemical techniques in pseudo-chilblain lesions, purpuric maculopapular exanthema and erythema multiforme. However, polymerase chain reaction (PCR) techniques from the skin samples have been negative in every conducted study.