Coronavirus disease 2019（COVID-19） is an infectious disease caused by the new coronavirus（SARS-CoV-2） that originated in China in December 2019, and it has been reported that it mainly causes respiratory symptoms but also exhibits various skin symptoms associated.
The skin lesions are classified into six patterns represented by the acronym “GROUCH” : Generalized maculo- popular. Grover’s disease and other papulo-vesicular eruptions, livedo Reticularis, Other eruptions, Urticarial, and CHilblain-like. Patients with chilblain-like lesions were younger and had a lower incidence of systemic symptoms. Purpuric and livedoid lesions have been suggested to occur more frequently in elderly patients with severe COVID-19.
COVID-19 often leaves sequelae that last weeks to months after initial recovery. It was estimated that 80％ of the infected patients developed one or more long-term symptoms. The five most common symptoms were fatigue（58％）, headache（44％）, attention disorder（27％）, hair loss（25％）, and dyspnea（24％）. A major cause of hair loss after COVID-19 is considered as telogen effluvium, defined by diffuse hair loss after the systemic stress or infections. Most patients with hair loss recovers within 6 months.
Skin reactions have been reported after COVID-19 vaccination as well. The most reported cutaneous finding was a delayed large local reaction “COVID-arm” a median of 7 days after vaccine. The pathophysiological mechanism is still unknown, but it is overwhelmingly common in women, suggesting a cross-reaction between polyethylene glycol, a component of cosmetics, and injection components. In additions, there have been reports of skin rashes similar to those after COVID-19 infection and the aggravation of psoriasis or other skin conditions.
The mechanism of the cutaneous manifestations is still unclear. We must remember to ask about a history of COVID-19 infection and vaccination status at the time of consultation
