How to recognise the different types of skin imperfections?

The term "imperfections" is often misused. It is sometimes used to refer to areas of dry or shiny skin, or even a dull complexion. However, it actually refers to small temporary impurities, caused by specific factors, which can appear on the face and certain parts of the body.

acne is most frequently used. However, there are many other skin issues associated with imperfections, which can appear at any age. Among those commonly encountered, we have:

• Visible Pores : Dilated pores are defined as a skin imperfection. Indeed, they are dynamic structures whose size can fluctuate, although it is genetically determined. Thus, dilated pores manifest as a micro-depression on the surface of the facial skin with a "mandarin skin" appearance. According to a study, skin pores are said to be "visible" and "enlarged" when their diameter oscillates between 0.06 and 0.1 mm2.

  This increase in pore size can be associated with three potential factors, namely an increased sebum production, a loss of skin elasticity with age or an increase in the size of hair follicles (thickness of the hair). This dilation makes the pores more susceptible to becoming blocked, thus leading to the formation of comedones and pimples. Most enlarged pores are found on the nose and the medial aspects of the cheeks;

  

• Blackheads (open comedones): Blackheads are classified as a common form of non-inflammatory mild acne. They are easily recognisable by their black colour, which comes from the melanin contained in the sebum that oxidises when it comes into contact with the surrounding air, forming a black plug on the surface of the pilosebaceous follicle.

  Particularly stubborn and difficult to eliminate, blackheads form as a result of the obstruction of skin pores by an excessive secretion of sebum (hyperseborrhoea) and/or dead cells (hyperkeratosis). They primarily appear in the T-zone of the face, that is, around the nose, on the forehead, and on the chin, which are the areas of the skin with the most sebaceous glands. Often confused with sebaceous filaments, it's important to correctly distinguish between them.

  

• Whiteheads (closed comedones)) : Whiteheads appear as small bumps, usually less than 3 mm in diameter, almost invisible to the naked eye. They are flesh-coloured, round, raised and non-inflamed, caused by the congestion of follicular openings due to an excess of dead skin and sebum.

  They typically appear around the hairline, on the tops of the cheeks, and on the chin, but can be found anywhere on the body. Unlike blackheads, closed comedones form beneath the skin's surface, thus preventing their oxidation. However, if they are picked at or if conditions are favourable for an infection, they can develop into a papule or a pustule;

  

• Papules (red spots): Papules are the most common but less severe inflammatory acne lesions. They appear as small red protrusions, due to inflammation, with a diameter less than 1 cm, and do not contain any purulent material.

  They form when sebum, unable to flow freely, accumulates in the hair follicle, creating an environment conducive to the colonisation of the bacteria Cutibacterium acnes, formerly listed under the name Propionibacterium acnes, but also causes the rupture of the pore walls to which the skin responds with a visible inflammatory response ;

• Pustules (white spots) : Unlike papules, pustules are small bumps, measuring between 5 and 10 mm in diameter, with a white or yellow centre filled with pus due to its composition of inflammatory cells, indicating a bacterial, fungal or viral infection, and a red outline.

  Their cause? An accumulation of sebum and keratinocytes, and the proliferation of the bacteria Cutibacterium acnes, just like papules. Although they can easily subside, they tend to recur;

  

• Nodules: Present in the most severe forms of acne, nodules are dome-shaped infected lesions, palpable to the touch, larger in size (measuring approximately 1 - 6 mm in diameter), flesh-coloured, white or red, which can be physically painful, and develop deep within the skin. They generally heal leaving scars. Their appearance implies increased activity of the sebaceous glands, abnormal keratinisation of the follicles, the action of microorganisms, and subsequent inflammation;

  

• Cysts: Much like nodules, cysts are considered a form of severe acne. Generally painless, these are pockets of tissue with thin walls containing a fluid or semi-fluid substance with an epithelial lining, and they develop deep within the skin. However, a rupture in the microcyst's wall can make it sensitive to touch and cause inflammation, leading to the appearance of a red and purulent spot;

• Brown Spots : It's not just pimples and blackheads that are considered the only skin imperfections we can encounter. The pigment spots, namely the solar spots, the melasma and the post-inflammatory hyperpigmentation marks, are also considered as skin imperfections. They appear as spots that are flat, asymptomatic, ranging in colour from light brown to dark brown, usually with irregular edges and can vary from a few millimetres to several centimetres in diameter.

  This abnormal skin pigmentation results either from an increase in melanin content by the melanocytes, or from an abnormal distribution of it within the skin. Spots most often appear on the face, the back of the hands, the décolletage or in the folds of the skin. This disorder is favoured by various factors such as sun exposure, hormones, or even repeated skin friction ;

  

• Residual Scars: Beyond spots and brown patches, scars are also considered as skin imperfections. It happens that some acne spots leave lasting marks, especially if they have been handled inappropriately. These scars form when new collagen develops rapidly and deposits to heal an inflammatory lesion and prevent infection. Unfortunately, acne scars never completely disappear, even though their appearance tends to generally improve over time. Ice pick, atrophic (indented), hypertrophic (raised)... there are different types of acne scars.

  

Until now, it is still commonly believed that poor daily hygiene is the main cause of these skin issues. However, this is not always the case. Other triggering factors, whether internal or external, can contribute to a blemished skin, such as:

• Hereditary predisposition: Genetics and family history appear to play a dominant role in the onset of acne, particularly severe acne. Indeed, several studies show that acne appears earlier and is more severe in individuals with positive family histories. One study even identified two new loci, 11p11.2 and 1q24.2, which are thought to be involved in the metabolism of androgens, inflammatory processes, and scar formation in severe acne, thus highlighting another risk factor influencing acne.

  There is also a clear genetic predisposition in patients suffering from melasma, a common form of hyperpigmentation. Indeed, 60% of those affected report that family members also suffer from it. Similarly, genetics predominantly determine the size of skin pores;

• Skin Type: Combination to oily skin types are most likely to exhibit blemishes such as blackheads, comedones or pimples, as they secrete more sebum than normal, creating a favourable environment. Of course, they can also appear on other skin types under the influence of several factors;

• Aging: As we age, the skin loses its elasticity, thus the skin around the pores becomes less tight, which can then lead to an increase in their size and make them more visible.

  Furthermore, as we age, the skin's cellular renewal process slows down. Consequently, dead cells remain on the skin's surface instead of shedding, leading to their accumulation, the blockage of pores (and also their enlargement), and thus the formation of spots;

• Hormonal Disorders: Hormones are one of the main causes of skin imperfections. For instance, during puberty, the body produces more male hormones (testosterone, androgen), which in turn boosts the production of sebum in the sebaceous glands. As a result, men tend to suffer more from acne during adolescence than women. However, in adulthood, women are more affected by acne than men, which can be largely attributed to a hormonal component.

  Although their levels stabilise over the years in men, in women, they continue to fluctuate, particularly with the onset of menstruation (premenstrual syndrome), during pregnancy, at menopause or even following the cessation of hormonal contraception. A study has shown that a high serum level of progesterone, but a low level of oestrogen, was found in patients suffering from common acne.

  UV rays are not the only factors that promote the appearance of brown spots on the skin. Hormonal factors also play a role in skin pigmentation defects. Studies have shown that under the influence of female hormones, namely oestrogen and progesterone, an over-stimulation of melanocytes has been observed;

• Chronic sun exposure: Overexposure to the sun can cause dehydration and dry out the skin. In response to this imbalance, the skin will start to produce more sebum. Similarly, indirectly, the sun is also a risk factor in the dilation of skin pores. It weakens the structure of the dermis, damaging the collagen and elastin fibres. Less firm and flexible, the dermal structure surrounding the pores then collapses and their size widens.

  Ultraviolet rays also constitute the main exogenous factor capable of altering the normal pigmentation of the skin. In response to the mutagenic effects of the sun's UV rays, the skin secretes melanin to protect the nucleus, and therefore the DNA, of the keratinocytes in the basal layers of the epidermis, acting as a natural sunscreen. Furthermore, the penetration of the sun's UV rays leads to an increased production of free radicals, which would stimulate the production of melanin to protect cells from their harmful effect;

• Imbalanced Diet: There is evidence that diet can promote the development of acne. Indeed, studies have assessed the impact of the glycaemic index of various foods on the skin, revealing that individuals following a high glycaemic load diet have more acne lesions. This is caused by a significant production of insulin to lower blood sugar levels, which in turn increases androgen levels, thereby promoting sebum secretion.

  Similarly, several studies have demonstrated a positive association between the consumption of dairy products and the prevalence of acne. More specifically, they have shown that whey proteins and casein could contribute to the development or exacerbation of acne, by triggering sebum production. Furthermore, acne can be caused by the consumption of foods high in free fatty acids, which can promote the proliferation of P. acnes .

• Sleep Quality: A sleep duration of less than 8 hours per day could be a risk factor for acne. Indeed, studies have shown that a lack of sleep (sleep duration ≤ 5 hours) was correlated with an increase in transepidermal water loss compared to individuals with good sleep quality (sleep duration between 7 - 9 hours), indicating an impairment of the skin barrier. In such a situation, the skin's defence system against external aggressions is weakened, which can lead to skin problems such as acne, but also an increase in sebum production;

• Touching the face: Generally, we touch our face about 3,000 times a day, although this varies from person to person. However, our hands come into contact with numerous surfaces throughout the day that harbour bacteria and other dirt that is not good for the skin. This can potentially lead to an increase in skin imperfections. Similarly, handling and popping pimples significantly increases the risk of damaging the skin and thus promoting the formation of scars.

• JEREMY A. & et al. Comedone Formation: Causes, Clinical Manifestation, and Treatment. Clinics in Dermatology (2004).

• CHUNG K. & others. Sebum production as a factor contributing to the size of facial pores. British Journal of Dermatology (2006).

• KITAHARA T. & al. Age-related alterations in the epidermal structure surrounding facial pores. Journal of Dermatological Science (2008).

• WILLIAMS H. C. & others. Epidemiology of acne vulgaris.British Journal of Dermatology (2012).

• YOUN S. W. & co. Sebum, acne, skin elasticity, and gender difference - which is the major influencing factor for facial pores? Skin ResearchandTechnology (2013).

• LAI W. & al. Two new susceptibility loci 1q24.2 and 11p11.2 confer risk to severe acne.Nature Communication(2014).

• SEO S. J. & co. Facial pores: definition, causes, and treatment options. Dermatologic Surgery (2015).

• CHEN W. & et al. Sex hormones and acne. Clinics in Dermatology (2017).

• LENORMAND C. & al. Hyperpigmentations. Annals of Dermatology and Venereology (2019).

• HE L. & al. A review of progress on the influencing factors of acne: a focus on environmental characteristics. Frontiers in Public Health (2020).

• TAN J. & al. Effects of diet on acne and its response to treatment. American Journal of Clinical Dermatology (2020).

• VIE K. & al. Visible characteristics and structural modifications associated with enlarged facial pores. Skin Research and Technology (2021).