The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).53,54
FIGURE 6. Follicular papulopustular eruption (so-called maskne) distributed over the facial zones covered by a surgical mask.
DERMATOSES REVEALED OR AGGRAVATED BY COVID-19
Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.55 Psoriasis and acrodermatitis continua of Hallopeau,56 which may progress into generalized, pustular, or erythrodermic forms,57 have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.57 Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.58 The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.59 Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,60 possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.61 Lupus erythematosus, which may relapse in the form of Rowell syndrome,62 and livedoid vasculopathy63 also have been reported following COVID-19 infection.
SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES
In parallel with the rapid spread of COVID-19 vaccination,4 an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.65 Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.70 Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:
• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.70
• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.70
• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.70
• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.70