This summary addresses skin and oral mucosal manifestations of COVID-19. Refer to COVID-19 for a complete overview of COVID-19 illness, including general clinical features and range of severity, transmission, variants, differential diagnosis, laboratory tests, and therapy.
COVID-19: Several main mucocutaneous manifestations of COVID-19 have been described.
- Pernio-like lesions on the acral surfaces (also known as "COVID toes," pseudo-chilblains, and acute acro-ischemia). These manifestations occur in younger individuals late in disease course and usually follow a milder illness. Polymerase chain reaction (PCR) is often negative in these patients, and the timing of onset may be an explanation. Viral particles have been demonstrated within endothelial cells of affected areas, supporting that this cutaneous finding is a direct effect of the virus as opposed to quarantine-induced lifestyle changes (eg, inactivity and ongoing cold exposure in unheated homes). However, some debate remains on this subject; it is possible that some individuals have chilblain-like lesions as a result of infection with SARS-CoV-2 and some have true chilblains as a result of lifestyle changes in the setting of a global pandemic. Cryofibrinogenemia has been found in two-thirds of a series of 54 patients with COVID-related chilblains; further studies are needed to support cryofibrinogens as a potential pathogenetic factor.
- A vesicular eruption. This manifestation has been described predominantly in middle-aged patients with moderate disease severity and lasted around 10 days.
- An urticarial eruption. Acute urticaria is an early sign of infection. Urticaria has also been reported to predate viral symptoms by up to 48 hours. Angioedema has been rarely reported. Urticarial eruptions also include urticarial vasculitis.
- A macular or papulosquamous eruption. For both the urticarial and maculopapular eruptions, patients tend to present with more severe disease. In the largest study of skin manifestations of COVID-19, rash was present at the onset of other symptoms and lasted about 6-8 days.
- Livedo or retiform purpura. Transient livedo has been seen in milder illness, but livedo racemosa or retiform purpura that may be complicated by skin necrosis may be seen in individuals with severe disease. A series of 4 such cases with these skin findings manifested evidence of a thrombotic state, including high D-dimer levels and suspected pulmonary emboli. Purpuric pressure ulcers have also been reported in hospitalized patients. Risk factors included obesity, impaired mobility due to critical illness, incontinence, and malnutrition, and their presence seems to be independent of thrombotic vasculopathy.
A study reporting data from an international registry of individuals with confirmed COVID-19 found that the most commonly associated dermatologic finding was a morbilliform eruption. Pernio-like lesions were the second most common and were generally associated with mild disease. The least common skin finding in patients with COVID-19 was livedo reticularis; this was seen only in patients with severe COVID-19.
A large 2024 population-based retrospective cohort study demonstrated a 50.8% increased risk of autoimmune bullous disorders (pemphigus vulgaris more than bullous pemphigoid) developing within 3 months after COVID-19 infection compared with controls, whereas COVID-19 vaccination was associated with a decreased risk of autoimmune bullous disorders, mainly pemphigus, by almost half.
Multisystem inflammatory syndrome in children: Multisystem inflammatory syndrome in children (MIS-C) is a serious and potentially life-threatening syndrome that occurs 2-6 weeks after COVID-19 infection in children. Most patients are asymptomatic or only mildly symptomatic during acute infection. The typical presentation of MIS-C is fevers for 3-5 days, gastrointestinal symptoms (abdominal pain, vomiting, diarrhea), KD-like mucocutaneous features, and shock. Other features include sore throat, myalgia, swollen hands / feet, and lymphadenopathy. Cases of multisystem inflammatory syndrome in adults (MIS-A) are also reported.
Post-COVID conditions: As more is learned about the long-term effects of COVID-19 (post-COVID conditions, or "long COVID") in some individuals, durable cutaneous manifestations have been observed. While morbilliform and urticarial eruptions were found to resolve within days, one study of an international registry found that 6.8% of those with chilblain-like lesions have persistence greater than 60 days. Papulosquamous eruptions of COVID-19 have generally been reported to resolve within a few weeks, but a case of a patient with such an eruption for 70 days has been reported in an international registry. Telogen effluvium is reported after COVID-19 infection, estimated in up to 10% of patients in one paper.
Related topic: cutaneous reactions after COVID-19 vaccination
