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Comment reconnaître les différents types d'imperfections ?

How To Recognize the Different Types of Blemishes on Skin.

Blackheads, pimples, pigmentation spots…  Different types of skin blemishes can take many forms, affecting the quality of skin and complexion immediately. But, what is a skin blemish? It is important to be aware of their characteristics, so you can better identify them, understand how to manage them, and provide the right care for clear, even-toned skin. Let's take a look at them together in this article.

“Skin Blemishes”: Meaning.

What is a skin blemish? The word “blemish” is often misused. It is sometimes used to refer to dry or shiny areas of skin, or to dull complexions. However, it actually refers to small, temporary impurities, caused by specific factors, which can appear on the face and certain parts of the body.

Similarly, when it comes to a blemish, acne is the term most frequently used. Yet, there are many other types of skin blemishes, which can appear at any age. Among those frequently encountered are :

  • Visible pores: Dilated pores are defined as blemishes on skin. They are dynamic structures whose size can fluctuate, even though they are genetically determined. Thus, dilated pores manifest themselves as a micro-depression on the surface of the facial skin, with a “tangerine skin” appearance. According to one 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 increased sebum production, loss of skin elasticity with age, or an increase in the size of hair follicles (hair thickness). This dilation makes pores more susceptible to clogging, leading to the formation of blackheads and pimples. Most enlarged pores are found on the nose and medial aspects of the cheeks;

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

    Particularly stubborn and difficult to remove, blackheads form when the skin's pores are blocked by large quantities of sebum (hyperseborrhea) and/or dead cells (hyperkeratosis). They appear mainly on the T-zone of the face, i.e., around the nose, forehead and chin, the areas of the skin with the most sebaceous glands. Often confused with sebaceous filaments, be sure to distinguish between them.

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

    They typically appear around the hairline, on the upper cheeks and chin, but can be found anywhere on the body. Unlike blackheads, closed comedones form below the surface of the skin, preventing their oxidation. However, if squeezed or infected, they can develop into papules or pustules;

  • Papules (red pimples): Papules are the most common but less serious inflammatory acne lesions. They take the form of small red excrescences, due to inflammation, with a diameter of less than 1 cm, and containing no purulent matter.

    They form when sebum, no longer able to flow freely, accumulates in the hair follicle, creating an environment conducive to the colonization of the Cutibacterium acnes bacterium, formerly known as Propionibacterium acnes, but also causing rupture of the pore wall, to which the skin retaliates with a visible inflammatory response;

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

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

  • Nodules: Present in the most severe forms of acne, nodules are infected, dome-shaped lesions, palpable to the touch, larger (measuring around 1 - 6 mm in diameter), flesh-colored, white or red, which can be physically painful, and which develop deep down. They usually resolve with scarring. Their appearance implies increased sebaceous gland activity, abnormal follicle keratinization, the action of microorganisms and subsequent inflammation;

  • Cysts: Like nodules, cysts are considered a severe form of acne. Generally painless, they are thin-walled pockets of tissue containing fluid or semi-fluid material with an epithelial lining, and develop deep down. A rupture in the wall of the micro-cyst can, however, make it sensitive to the touch and cause inflammation, resulting in the appearance of a red, purulent pimple;

  • Dark spots: Pimples and blackheads aren't the only skin blemishes we encounter. Pigmentation spotssun spots, melasma and post-inflammatory hyperpigmentation marks – are also considered blemishes on skin. They take the form of flat, asymptomatic spots, light to dark brown, generally with irregular edges and ranging from a few millimeters to several centimeters in diameter.

    This abnormal skin coloration results either from an increase in melanin content by melanocytes, or from an abnormal distribution of melanin in the skin. Spots most often appear on the face, back of hands, décolleté or folds. This imbalance is encouraged by factors such as sun exposure, hormones and repeated rubbing of the skin;

  • Residual scars: In addition to pimples and dark spots, scars are also considered skin blemishes. Some acne pimples can leave lasting marks, especially if they've been tampered with. These scars form when new collagen rapidly develops and deposits to heal an inflammatory lesion and prevent infection. Unfortunately, acne scars never completely disappear, although their appearance tends to improve over time. Ice-pick, atrophic (sunken), hypertrophic (raised)... there are different types of acne scars.

Where Do Blemishes on Skin Come From?

To this day, people still think that poor daily hygiene is the main cause of the appearance of these different types of skin blemishes. This is not always the case. But what is a skin blemish’s cause? There are other triggers, both internal and external, that can promote blemished skin, such as :

  • Hereditary predisposition: Genetics and family history seem 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 people with a positive family history. One study has even identified two new loci, 11p11.2 and 1q24.2, which are thought to be involved in androgen metabolism, inflammatory processes and scarring in severe acne, highlighting yet another risk factor influencing acne.

    There is also a clear genetic predisposition in patients with melasma, a common form of hyperpigmentation. In fact, 60% of sufferers report having family members with the condition. Genetics also plays a major role in determining skin pore size;

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

  • Aging: As skin ages, it loses its extensibility, so the skin around the pores becomes less tight, which can lead to an increase in their size and make them more visible.

    What's more, with age, skin cell renewal slows down. As a result, dead skin cells remain on the skin's surface instead of shedding, causing them to accumulate, clogging pores (and enlarging them as well) and leading to the formation of pimples;

  • Hormonal disorders: Hormones are one of the main causes of the appearance of blemishes. For example, during puberty, the body produces more male hormones (testosterone, androgen), which boosts sebum production in the sebaceous glands. As a result, men suffer more from acne in adolescence than women. On the other hand, in adulthood, women are more affected by acne than men, which can be explained by a hormonal component.

    While their levels stabilize over the years in men, in women they continue to fluctuate, notably at the onset of menstruation (premenstrual syndrome), during pregnancy, at menopause or following discontinuation of hormonal contraception. One study showed that high serum progesterone levels, but low estrogen levels, were found in acne vulgaris patients.

    UV rays aren't the only factors promoting the appearance of dark spots on the skin. The hormonal factor is also one of the causes of skin pigmentation defects. Studies have shown that melanocytes are hyper-stimulated by the female hormones estrogen and progesterone;

  • Chronic sun exposure: Overexposure to the sun can lead to dehydration and dry skin. To counteract this imbalance, the skin produces more sebum. Indirectly, too, the sun is a risk factor in the dilation of skin pores. It weakens the structure of the dermis, damaging collagen and elastin fibers. Less firm and supple, the dermal structure surrounding the pores sags and their size enlarges.

    Ultraviolet rays are also the main exogenous factor capable of modifying normal skin pigmentation. Faced with 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. In addition, penetration of the sun's UV rays leads to increased production of free radicals, which in turn stimulates melanin production to protect cells from their harmful effects;

  • Unbalanced diet: There's evidence that diet promotes the development of acne. In fact, studies have evaluated the impact of the glycemic index of various foods on the skin, revealing that people on a high-glycemic-load diet have more acne lesions, caused by a high production of insulin to lower blood sugar levels, which in turn increases androgen levels, promoting sebum secretion.

    Similarly, several studies have demonstrated a positive association between dairy consumption and acne prevalence. More specifically, they have shown that whey protein and casein can contribute to the development or aggravation of acne, by triggering sebum production. In addition, acne can be caused by the consumption of foods rich in free fatty acids, which can promote the proliferation of P. acnes ;

  • Sleep quality: Less than 8 hours' sleep a day is 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 people with good sleep quality (sleep duration between 7 – 9 hours), signalling an alteration in the cutaneous barrier. When faced with such a situation, the skin's defense system against external aggression is weakened, which can lead to skin problems such as acne, as well as an increase in sebum production;

  • Touching the face: As a general rule, we touch our faces around 3,000 times a day, although this varies from person to person. Our hands come into contact with numerous surfaces throughout the day, harboring bacteria and other dirt that are not good for the skin. This can lead to the multiplication of blemishes on skin. Likewise, handling and popping pimples considerably increases the risk of damaging the skin and thus promoting scarring.

Sources :

  • JEREMY A. & al. Comedone formation: Etiology, clinical presentation, and treatment. Clinics in Dermatology (2004).

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

  • KITAHARA T. & al. Age-related changes in the epidermal architecture around facial pores. Journal of Dermatological Science (2008).

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

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

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

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

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

  • LENORMAND C. & al. Hyperpigmentations. Annales de Dermatologie et de Venereologie (2019).

  • HE L. & al. A review of advancement on influencing factors of acne: an emphasis on environment 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 relating to enlarged facial pores. Skin Research and Technology (2021).


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