A multimodal approach to acne mechanica associated to medical face masks using clinical examination, fluorescent photography, and in vivo reflectance confocal microscopy.

With yet unclear pathogenesis, acne mechanica associated to medical face masks(MFM) gained increased attention during the COVID-19 pandemic. Between November 2021-January 2022 we conducted an exploratory, cross-sectional study evaluating the differences between the glabella and cheek-chin junction using clinical examination, fluorescent photography (FP), videodermatoscopy and in vivo reflectance confocal microscopy (RCM). Medical doctors from our country and 6th year medical students were invited. Participants self-identified as consistent MFM users during work hours. We analysed 19,432 images from 14 consecutive subjects, 11 females, 3 males, mean age,29.93 years (SD = 4.69). Clinical examination revealed more inflammatory lesions on the cheeks and chin (+ 9.35;95%CI + 2.31to + 16.39;d = 0.76, P =.01). FP considered ultraviolet red fluorescing spots(UVRFs) from the glabella and the cheek-chin junction, with significantly more spots in the former (+ 5.43;95%CI + 2.64to + 8.20; d = 1.12; P =.001). The average area in mm2 covered by the spots was significantly larger in the glabella (+ 3.26;95%CI + 1.43to + 5.08;d = 1.02; P =.002). RCM considered 9546 follicles, 4966 from the glabella, and 4580 from the cheek-chin junction. The cheek-chin junction had a significantly higher proportion of hyperkeratotic follicles than the glabella (+ 9%;95%CI + 2%to + 16%;d = 0.79;P =.01). In the dermal-epidermal junction, the cheek-chin region had a significantly higher proportion of follicles with signs of inflammation than the glabella (+ 10%;95% CI + 3%to + 18%; d = 0.80; P =.010). Perifollicular stratum corneum thickness was significantly lower in the cheek-chin junction, 19.56 μm (SD = 4.84) compared to the glabella, 24.25 μm (± 4.93) (-4 μm;95% CI-1 μm to- 8 μm; r =.88; P =.01). The distribution of UVRFs, known to correlate with microbial activity and sebum production, is similar to pre-pandemic studies, suggesting that in acne mechanica associated to MFM, follicular hyperkeratinisation, inflammation, and irritation, may outweigh other possible alterations.