Pityriasis alba secondary to prolonged use of face mask

Dear Sir,

Pityriasis alba is a common dermatosis in children. Considered a form of mild eczema with post-inflammatory hypopigmentation, the risk factors of this condition include atopy, swimming, prolonged sun exposure and prolonged or frequent showering, while the use of sunscreen can prevent it.[1] Due to the COVID-19 outbreak, many countries have recommended the use of face masks to reduce the transmission of the virus. We describe a novel case of pityriasis alba arising on the lateral cheeks that was attributed to the friction caused by the uneven edge of a cloth face mask after prolonged use.

A previously healthy 8-year-old Chinese girl with a past medical history of allergic rhinitis presented with a 1-month history of asymptomatic white patches on her lateral cheeks bilaterally. Due to the COVID-19 pandemic, as a requirement for attending school and venturing out of home, she had worn a cloth face mask for 6–7 hours a day for five months before the symptoms developed. She was also an active swimmer and had resumed swimming after the nationwide partial lockdown (known as ‘circuit breaker’) ended. A systemic review was otherwise unremarkable. Family history was significant for atopy, with her father having atopic dermatitis. There was no prior treatment.

On examination, there were hypopigmented macules on the lateral cheeks bilaterally [Figures 1a and b]. The affected area corresponded to the uneven edge between the elastic straps of the face mask that she was wearing regularly [Figures 2a and b]. There were no other areas of hypopigmentation on the rest of her skin and a general physical examination was otherwise unremarkable.

Figure 1.

Photographs show poorly demarcated hypopigmented macules on the (a) right and (b) left lateral cheeks.

Figure 2.

Photographs show the (a) right and (b) left parts of the patient’s face covered by the uneven areas between the elastic band of the cloth face mask (circled).

She was diagnosed with pityriasis alba secondary to prolonged irritation caused by the uneven edge of the cloth face mask and was treated with moisturisers and tacrolimus 0.03% ointment and advised to apply sunscreen during her swimming lessons. She was also advised to use a surgical face mask without the elastic band, instead of the cloth face mask. The lesions resolved after a month.

Prolonged mask wearing has been well reported to be associated with other dermatological conditions, such as pressure urticaria, acne, seborrhoeic dermatitis, contact dermatitis and rosacea.[2,3] Other common complaints associated with wearing face masks include itch, skin dryness, pain and facial erythema.[4] Rarer complications include extension of tinea faciei lesions into areas in contact with the mask, koebnerisation of pre-existing molluscum contagiosum infection and insect bite reaction.[4]

Rosner reported that prolonged mask wearing by healthcare workers was associated with shearing and breakdown of the stratum corneum.[5] Our patient’s frequent swimming and showering could have exacerbated the skin barrier dysfunction, and removed skin-protective factors, such as epidermal defensin.[1] We postulate that this can increase the skin’s susceptibility to ultraviolet light when the patient subsequently removes her face mask. Ultraviolet exposure reduces melanocyte activity and increases inflammatory cytokines, which promote hypopigmentation.[6] Pityriasis alba is associated with increased expression of genes associated with oxidative stress, such as IL-6 and HMOX1, SOD1 and IFNγ, consistent with increased ultraviolet exposure.[6]

Another possible explanation is the increased humidity over the skin from mask wearing, due to occlusion of the pilosebaceous ducts.[7] This may further damage the stratum corneum, promoting increased trans-epidermal water loss. The increased humidity and sebum secretion may also promote the growth of microorganisms, such as Staphylococcus and Propionibacterium acnes, which may be linked to pityriasis alba.[1]

In conclusion, pityriasis alba is a common paediatric dermatosis, traditionally associated with increased sun exposure, swimming and bathing. Our case report highlights that prolonged face mask use during the COVID-19 pandemic can also lead to pityriasis alba.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil