2. Skin manifestations associated with thrombovascular events
and vascular pathologies
COVID-19 exanthems have also been reported with petechiae and low
platelet count resembling dengue (30). In
two patients, unilateral lesions on the thigh resembling livedo
reticularis or erythema ab igne have been described with
microthromboses discussed as possible etiology (Figure 3A) (31).
Chilblain-like skin lesions have been frequently reported to be
associated with COVID-19 (22,32,33,34) (Figure 3B(32)). They appear in
up to 19% of patients, typically in mildly affected ones, and late in
the evolution of the disease (22,34). Vesicles, pustules and erosions on
these violaceous plaques may occur (34). In Spain they were observed in
19% of 375 cases (22).
Seven patients had cutaneous acro-ischemia including finger and toe
cyanosis, skin bulla and dry gangrene associated with COVID-19
infection-induced hypercoagulation including definitive DIC in four
patients. Five of these patients finally died (Figure
3C)(35). A catastrophic microvascular
injury syndrome mediated by activation of complement pathways and an
associated procoagulant state were described in severe COVID-19 with
purpuric skin rash in 3/5 patients (36).
In conclusion, the prevalence of cutaneous manifestations in COVID-19
patients has been reported between 0.2%, 4.9% and 20.9% (4,21,27).
Most skin manifestations resemble cutaneous involvement commonly
occurring during viral infections, i.e. erythematous rash and acute
urticaria. Drug exanthems have to be considered as differential
diagnosis (15). Vesicular varicella-like
exanthems may be more specific for COVID-19. Flexural distribution, and
petechia as well as erythema ab igne-like lesions have been described.
Violaceous, infiltrated painful plaques resembling chilblains have been
frequently reported and discussed as typical manifestations. Necrotic
lesions occurred in older and in severely ill patients with increased
mortality (22). Cutaneous acro-ischemic microthromboses and small blood
vessel occlusion have to be further explored for their causality and
specificity for COVID-19 manifestations.