The world is going through a pandemic of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS CoV-2) infection which cause the Coronavirus Disease-19 (COVID-19) since 2019. By March 2020, the World Health Organization (WHO) stated the disease as a pandemic due to its global spread and announce some recommendation of health protocols, such as wearing a mask and keeping personal hygiene. This is related to the transmission of the disease through droplets and air that people breathe [1-2]. 

The mask wearing activity become a serious concern of the internet users by the reported adverse effects of daily mask usage, including the acne outbreaks [1,3-4]. The internet then called the outbreaks as Maskne, derived from the word Mask and Acne [1]. Furthermore, the phenomenon become a global issue over the internet, as the outbreaks reported is worsen, particularly among the medical workers. This phenomenon lead to confusion and hesitation among the society to continue wearing their mask [3].

Maskne could bring a significant impact on people, physically and psychologically [4]. Physically, Maskne makes the patients feel uncomfortable and suffer from the sensations of the Acne, making it more difficult to maintain using the mask [5,1-2]. On the other hand, the psychological adverse effect could lead patients to further feel low on self-esteem, anxiety, and even depression [1,4,6]. This phenomenon concerns clinicians, to be able to communicate the basic mechanism, management, and also ways to prevent the outbreak of Maskne [3]. The right management and explanations would be beneficial to embrace the global society to keep wearing their mask and prevent further transmission of the disease.

Definition of Acne

Acne is a disease of the skin, manifested as an acute to chronic inflammation [7]. National Institute of Arthritis and Musculoskeletal and Skin Disease enhances the definition of Acne as an inflammation caused by hair follicle blockage due to dead skin cells and oil clogs, which later causing an outbreak on the skin surface [8]. It is also characterized by the appearance of comedones papules, pustules, or even nodules and cysts in the more severe degrees of the disease [6]. Acne predominantly found on the area in which hair follicles exist. It is commonly known as Acne Vulgaris [7].

Prevalence of Acne

Acne is a highly prevalent skin disease. It is previously expected to be the eighth most prevalent disease worldwide [9]. Acne occurs in 85-95% of adolescence with various degrees [9.6]. The prevalence is more likely to occur at the age of 12-24, contributed as much as 85% of the Americans [6]. The number, however, expected to decrease over 25 years old. There are a lot of discussions among studies to significant differences between sexes in the prevalence of Acne [9].

Due to its common widespread globally, Indonesia also reported the similarly high number of disease prevalence among the society. Sibero, et al. [10] reported the prevalence of the disease among Indonesians as high as 90% in the 2009, increased as much as 30% within three years, with 60% prevalence in 2006 [10]. Kristiani, et al. [11] also reported that 80% of the adolescences in Indonesia had the disease. The Incidence of Acne in Indonesia was also presented to occur among the 14-17 years old female teenagers and 16-19 years old male teenagers, which accounted up to 60% [11].

Types of Acne

Acne presented in a lot of different types, which can be indistinguishable by the manifestation of the signs and symptoms. Different types of Acnes shared similar characteristics to Acne Vulgaris as the bigger term of the disease. Several studies classified acne types based on their etiologies, including Occupational Acne, Drug-induced Acne, Cosmetic Acne, or Mechanical Acne [12]. Another common way to classify Acnes are based on their appearance, such as Acne Conglobata, or based on the patients, such as Neonatal Acne, Infantile Acne, Tardive Acne, or Juvenile Acne [1].

Basic Mechanisms of Acne

The exact Mechanism of Acne has not been well established. There are a lot of factors contributing to the disease pathogenesis, and not every aspect of the mechanism is well understood. However, some studies hypothesized that there are four contributing factors that are postulated as the major pathway of Acnogenesis. The four main factors that contribute to the occurrence of Acne include: Increased sebum production, hypercornification of the pilosebaceous ducts, Abnormal bacterial colonization, and Inflammation process [12,6].

Increased Sebum Production

Sebaceous gland is a part of pilosebaceous unit. They mainly contribute to produce lipid-rich excreted solute called sebum. The sebaceous glands drain the sebum to the hair follicles through the pilosebaceous ducts. Most of the sebaceous glands are found at the Acne-prone regions, such as cheeks, forehead, nose, back, and chest. 

The enhancement of sebum production is the most essential factor in the Acne outbreak mechanism. The production of the sebum is determined by the stimulus of Androgen hormone that is also influenced by the endocrine system. This is due to the sebaceous gland is one of the end organs of the Androgens. The greater amount of Androgen regulated to the pilosebaceous glands involved, the more sebum is produced [12,6]. This regulation occurs in both male and female individuals, even though female adolescences are the most susceptible [9]. 

Hypercornifiaction of the Pilosebaceous Ducts

The Androgens also play contribution to the proliferation of the pilosebaceous unit, including the sebaceous glands. The greater number of cells that are proliferated and died, followed by the excess sebum production, end up blocking the pilosebaceous ducts and therefore, the sebum release pathway. This mechanism led to the formation of comedones, a clogged pilosebaceous duct, which further complicate the sebum excretions. 

The comedones start as a microcomedones which invisible to the plain sight. Furthermore, comedones start to develop into a non-inflammatory lesion called comedone, which manifested as oxidized opened blackheads, or the closed whiteheads. Microscopically, comedones can be viewed as a dilated pilosebaceous ducts, filled with a mixture of cornified follicular epithelium, sebum, and microorganism. The formation of comedones also play a role for the clinicians to determine whether a lesion of inflamed skin is an acne eruption by simply looking at the appearance of comedones. [9,12,6].

Abnormal Bacterial Colonization

Human skin is a home of trillions of microorganisms, and most of them are commensal bacteria, such as Staphylococcus, Corynebacterium, and Propionibacterium. Microenvironmental changes of the skin, can directly alter the structure of the skin flora balance and develop a disease [13]. The most well-known microorganism contributes to the pathogenesis of the Acne is Propionibacterium acnes [12-13].

Propionibacterium acnes (P.acnes) is one of the two highly suspected microorganisms that determined the occurrence of Acne, along with the Staphylococcus aureus (S.aureus) which also a commensal bacteria of the skin. P. acnes known as an anaerobic bacterium and expected to metabolize lipid-rich sebum in the obstructed pilosebaceous ducts. The similar characteristic also occur on S.aureus, a facultative anaerobic, Gram-positive bacteria, which also have the lipid-breaking enzyme Lipase to fulfil their metabolism needs [13,6].

The colonization of the bacteria due to the imbalance of microenvironmental conditions and the lipid-rich sebum occlusion of the pilosebaceous duct create a great condition for the bacteria to grow and rapidly colonize, creating more damage towards the skin. The latter is shown by the activation of the immune system in response of the colonization, that creates local inflammations and further damage the skin [6].

Inflammation Process

The colony of the bacteria expected to trigger inflammatory reactions and the rupture of the comedones. This is possible because the bacteria have their own chemotactic factors as they produce low molecular weight polypeptides that attract innate immune systems with more immune cells to attack the bacteria colonization. 

The immune responses and the polypeptides, along with the chemotactic factors produced by the bacteria, attract more immune response, creating local inflammations of the comedones and rupture of the follicles. This process further attracts the adaptive immune system to create a more extensive inflammation to the skin. This further inflammation manifested as advance dermatoses, such as papules, pustules, or even nodules or cysts from the inflamed comedones [9,13,12,6].

Maskne Terminology

Maskne is a novel terminology, appear as the global pandemic of COVID-19 arises, which regulates people of the global society to wear mask as a daily habit to prevent the transmission of the disease. Based on the root terminology, it simply refers to Acne that occurs due to the mask wearing activity. The idea is gaining lots of notice, particularly among the medical workers, due to the occurrence of Acne on the mask-covered area [14-15].

Maskne globally challenges the world along with the risk of COVID-19. The terminology has become an internet trend since March 2020 as more social media users reported the outbreak [16,1] The regions that are first determined was notably at the nasolabial folds and middle cheeks [16], while on some other mask-user, it also occurs at the mandible, neck, and perioral regions [4,17]. Furthermore, some studies called the Maskne-prone regions as the O-Zone [17].

Maskne Classification

Based on the mechanism and manifestations, Maskne is classified as Mechanical Acne. Maskne is expected to occur due to the frictions between the skin surface with the mask material, and the alterations of skin microenvironments that lead to the outbreak of the Acne [14-15,1]. Gomolin, et al. [14] further explained the main difference between Maskne and Acne Vulgaris is due to the uncommon symptoms or milder degree of burning and pruritus sensation in Maskne, besides the limited region in which Maskne occurs [14].

However, there are still some controversies in which they should classify the Maskne. Some studies happened to approve the classifications, which particularly explains the limited regions of the outbreaks, [18,16]rather than the discrete locations in which pilosebaceous units are commonly found, such as the face, chest, and shoulders, which Acne Vulgaris normally appears. [13] Nevertheless, some studies also hypothesize Maskne as a part of Acne Tropicalis, due to their shared condition that involve tropical-climate alike microenvironment changes, [1,4]or Occasional Acne, as they are self-limited and occasionally appear and resolved [1].

Maskne Pathogenesis

The exact mechanism of Maskne is also not yet established, since Maskne is also derived from the Acne itself. Therefore, some studies expect the exact mechanism would be similar to Acne Vulgaris pathogenesis. Moreover, other studies also seem to notice another supplementary key feature that probably play a bigger role in the pathogenesis of Maskne.

Mask wearing activity apparently alter the skin condition and create a tropical sensation which later create a warm and more humid environment [1,17]. Han, et al. [16] explained that medical mask such as N95 respirator increased humidity as much as 93% within one hour of usage, which also described as pampered-like condition of the facial skin [16]. This lead us to understand the probable correlation of the mask wearing duration and the occurrence of Acne.

The increase of temperature and humidity lead to an increment of sebum production. This theory was explained in some other studies, that a rise of skin surface temperature as much as one degree of Celsius, lead to a rise of sebum excretion rate (SER) up to 10% [5,16,1]. furthermore, continuous rise of SER eventually lead to epidermal keratinocytes swelling and pilosebaceous follicle enlargement [14].

Increased SER, along with pilosebaceous glands enlargement led to further obstruct the ducts and facilitate the formation of comedones. The swelling of keratinocytes and frictions of mask material on the skin surface may later lead to production of more dead skin tissues, resulting in more build up debris and comedones formation [14,1]. Additionally, the friction of the mask also play role in irritating the skin surface, creating microinflammations within the skin. This condition worsen the comedones formation that lead to Acnogenesis, along with increased risk of other dermatoses as dermatitis, skin disruptions, or even ulcer formation [1,15].

Finally, mask-wearing activity also disrupt the skin microenvironment balance by increasing SER and humidity. Increased trans-epidermal water loss (TEWL), dehydration, and pH also lead to microorganism dysbiosis, creating a more suitable environment for bacteria to grow and further mechanism towards Acne development [14,16]. Moreover, mask-covered area would lead to poor oxygen circulation within the skin surface, which is beneficial for further growth of skin bacteria colonization, particularly P.acnes. 

Mask fabric material is also expected to play role in acne development. Teo [17] further explained that unbreathable, unhygienic, and rough surface of materials used, might further aggravates the acne development. Unsuitable mask material irritates the skin surfaces that promotes cells hyperplasia as well as cell apoptosis. Personal factor such as allergic or other immunologic conditions might also play role in further susceptibility to acne and further skin inflammations such as contact or seborrheic dermatitis. Besides, mask-user habit of touching faces with unhygienic hands, rubbing and adjusting the mask continuously, along with the use of comedogenic cosmetics also aggravate the risk [18,17,17] (Figure 1).

Figure 1: Simplified Chart of Acnogenesis

The diagram above explained the simplified pathogenesis of Acne. Started from the mechanism in ways of Acne may occur (white boxes) through the main four factors of Acnogenesis (colored stars):

• Increased sebum productions

• Hypercornification of the pilosebaceous ducts

• Abnormal bacterial colonization

• Inflammation process [12-13,6]. Mask-related risk factors also play contributions in Acnogenesis through its various pathways that resulted in the four main factors, creating the occurrence of Maskne (blue-colored box). Bacterial colonizations such as Propionibacterium acnes and Streptococcus aureus have the ability to produce polypeptides, such as lipase and hyaluronidase [13]. Individual factors are including genetics, previous medications, previous history of illnesses, and personal susceptibility to Acne [1]. FFA = Free Fatty Acid; NKC = Natural Killer Cells; PMN = Polymorphonuclear cells; SER = Sebum Excretion Rate

Manifestations and Diagnosis of Maskne

Based on the pathogenesis, Maskne can have similar clinical manifestations as Acne Vulgaris. Some common signs might appear as comedones, papules, pustules, or rarely nodulocystic lesions at the mask-covered area. The masked area includes cheeks, nasolabial folds, nose and nose-bridge, mandible, perioral, and some of the upper neck, or simply the O-zone [5,1,16].

Han, et al. [5] explained that Maskne commonly seen as papules and pustules, while nodulocystic lesions are less commonly seen at the forehead, submaxilla, and neck. This might related to the size of the pilosebaceous unit and follicles. Greater grades of inflammation also play a role in defining the severity of the disease [5,1]. The appearance of comedones also pathognomonic to define the dermatoses as acne lesions [1].

Patients might also complain about the itch and burning sensations that occur as well oily skins and other several dermatoses at the mask-covered area [5]. Moreover, some mask-wearing related issues might also complained by the patients, such as skin breakdowns and facial skin rashes [14,5,1-2]. It is also important to clinically address the systemic manifestations, such as headache, impaired cognition and disorientation, impaired vision, sleep deprivation, head and neck muscle strains, chest discomfort and dyspnea, and emotional distress. Those manifestations would lead us to acknowledge the habit of prolonged use of the masks [2].

Based on those manifestations, some studies also formulated diagnostic criteria for Maskne which later diagnosed as Mechanical Acne. Those criteria include the occurrence of Acne at the O-Zone, six weeks prior the initial mask wearing activity, deterioration previous history of acne, and being excluded from any differential diagnoses, such as dermatitis or folliculitis [17-18]. It is also essential to know the duration of daily mask-wearing, considering maskne commonly occurs within the prolonged users [2] that use the mask beyond the recommended duration [16,19].

Risk Factors of Maskne

Some aggravating risks of Maskne development are classified into internal individual’s skin condition and genetics, and also the external behavior, habit-related factors, as well as other factors involved. The internal individual skin’s condition defined as the previous condition of someone’s skin before wearing the mask. This includes the history previous acne and other skin diseases, the type of the skin based on the basic SER, and individual’s genetically susceptibility towards acne development [5,1,15]. This also included personal history of diseases or any medications that might as well interacted with the acne development.

The behavior-related and other factors are classified as external factors. These include duration of mask wearing activity, the habit of daily changing or cleansing the mask, face-washing routines, and skin-care products usage [5,1,15]. Other factors such as fabric-mask materials, type of the masks, environmental conditions, including ultraviolet (UV) exposures, might also play an important roles [15].

Management of Maskne

Non-pharmacological Approach: Management of Maskne might happen as simple as cleansing the face using antibacterial active ingredients soap. Facial soap is beneficial, not only to reduce the colonization of bacteria, debris, dead skin tissues, but also to increase the penetration of acne medication into the skin. It is not recommended to use body or regular soap, for its high pH could lower skin’s natural acidity and disrupt the skin barrier [1,15]. Alcohol, retinols, salicylic acid, and alpha hydroxy-acid containing skin care should be avoided, for its susceptibility to irritant dermatitis [14-15]. It is recommended to wash the face twice a day for a better result [1].

It is also recommended to gently apply non-oily, non-comedogenic moisturizers to maintain skin moisture and keep the microenvironment balanced. Natural ingredients moisturizers, sodium hyaluronate, and polyglutamic acid are recommended, due to their ability to maintain skin barriers and non-comedogenic characteristics. However, it is not recommended to use lanoline, petrolatum oil, mineral oil, or glycerol containing moisturizers, for their comedogenicity and susceptibility to occlude skin pores. Humectants and other prescription emollient devices (PED) such as ceramide are still allowed, as there is no hypersensitivity or contraindication acknowledged [15,17].

Sunscreen is recommended to be applied along with the moisturizers as moisturizing agents and prevent post-inflammation hyperpigmentation [1]. However, it is not recommended to use 50+ Sun Protective Factors (SPF) sunscreen and reapply multiple times daily for it is inconvenience. SPF has the characteristic of photodegradation while interacting with sweat and moistures under occlusion.  It is advisable to choose Ultraviolet Protective Factors (UPF) 50+ made for fabric-covered skin instead, and gently apply it at the lower half of the head. Water-resistant and lipophilic sunscreen is not advisable as they are highly comedogenic, particularly under occlusion [1].

Pharmacological Approach

Medical Management of Maskne is similar to the general type of Acne. While it is recommended to use botanical active agents, antioxidants, sebum regulating agents, and antimicrobial properties, the practice of spot acne treatment is not recommended. Spot acne treatment with such as benzoyl peroxide, salicylic acid, Sulphur, alpha-hydroxy acids, and retinoids are not recommended as they could trigger contact dermatitis under occlusions. However, it is allowed to use the treatment while not wearing a mask [17].

It is recommended to apply the topical medications for at least eight weeks using while not under occlusions, based on the severity of the disease. Topical retinoids, and topical antimicrobial properties, such as benzoyl peroxide, clindamycin, and erythromycin, is recommended for mild to medium degree of Maskne. Higher degree of Maskne might be eligible for using stronger medications such as systemic antibiotics and oral isotretinoin, while topical spot acne treatment is allowed to be given as well. Furthermore, it is recommended to use topical retinoids as a maintenance measure of the post-acne flare treatment[1].

Preventive Measures

Han, et al. [5] shared some behavioral recommendations on preventing Maskne, such as replacing surgical mask every four hours, replacing N95 respirator every three days, washing both hands before and after wearing or touching the mask, daily rubbing face with wet towel and moisturizers before and after wearing a mask, and using oil-control containing ingredients to cleanse the face. It is also recommended to put in sheets of wipes inside the respirator or masks, to absorb excess fluids, vapors, or oils as ventilations occurs [5].

The preventive measures of Maskne should not be limited to the facial issues. It is also important to focus on the duration of mask-using activity as well as the environmental factors. Rosner [2] advised that there should be a plausible work shift hours to reduce the exposures and the risk of Maskne [5]. It is also essentials to prevent prolong using the surgical mask to more than six hours, as the WHO recommendation [19]. In addition, the other negative adverse effects on physical and mental health related to the prolonged use of the mask also need to be considered [18-19].

Maskne  is a global phenomenon that rises along with the usage of mask-wearing activity due to the pandemic. It is important to address the problem by knowing the mechanism and ways to manage the disease to prevent further issues among the global society. Similar to the bigger terminology of the disease, Maskne has an almost identical mechanism as the Acne, as it was addressed as a part of Mechanical Acne. 

Further education should also be addressed to the society, particularly in the era of the pandemic, which people are recommended to wear a mask as a part of ultimate health protocols. Proper explanations would also acknowledge a better understanding towards the society to better handle and manage the problems. Lack of information would lead to hesitation of wearing the mask and also globally impact the transmission of the disease. 

Acknowledgements

Atma Jaya Catholic University of Indonesia for being the place I learn the basic science of dermatology and literature writing, along with  my family who supported me to publish this article.