Acne is a common skin condition that affects millions of people worldwide. Over 85% of adolescents have or will experience the physical and psychological effects of acne. From teenagers to adults, its presence can cause distress and diminish self-esteem. In this comprehensive article, we will delve into the various aspects of acne, including its potential causes, formation, types of lesions and link to potential prevention/treatment options.
What is acne?
“Acne is a chronic inflammatory disease of the pilosebaceous unit resulting from androgen-induced increased sebum production, altered keratinisation, inflammation, and bacterial colonisation of hair follicles by Cutibacterium Acnes.”
This means that acne is a condition caused by increased sebum (oil) production, changes in skin cell turn-over, inflammation, and increased levels of bacteria. Lesions forms when the hair follicle is blocked, and there is a build up of matter underneath pores.
Acne is still largely a mystery in the medical field due to its multitudes of causes. Each case varies from patient to patient, therefore, it is very hard to pin-point a specific treatment suitable for all.
Sites of acne lesions
- Forehead (common during puberty).
- Chin (common in adolescent women).
- Cheeks (most common area)
- Chest & shoulders (common in males).
- Upper back.
- Nose (blackheads, very common).
pathogenesis of Acne Vulgaris
When the pilosebaceous unit is faulty, the opening of the hair follicle (pore) becomes congested and inflamed. Pores are ‘little holes’ in the skin which are made up of a hair follicle and a sebaceous gland. If you look closely, you may be able to see them on your face. Sebaceous glands release sebum (oil) to moisturise the hair follicles and the stratum corneum (very top layer of the skin). When this mechanism works properly, the sebum is spread out over the skin and it remains healthy and nourished.
Acne is the result of this mechanism going astray.
Build up of impurities (both on the surface of the skin and inside the pilosebaceous unit) create a blockage of the pore. The pilosebaceous unit cannot detect whether a pore is blocked or not, therefore, the secretion of sebum does not stop. In closed comedones (typical form of acne) this results in a sub-dermal build up of sebum around the hair shaft.
What's happening beneath the surface?
- Hyperkeratosis increases corneocyte cohesiveness in the upper sebaceous follicle, which leads to microcomedo formation.
- Androgen stimulation of sebum production.
- Accumulation of shed keratin and sebum.
- Formation of whorled lamellar concretions.
- Cutibacterium Acnes proliferation, which up-regulates innate immune responses.
- Mild inflammation which increases upon rupture of comedo wall.
- Sebaceous lobule regression.
Life Cycle of Acne Vulgaris
There is little literature about how long the pathogenesis of acne takes, and how long it may take the lesions to heal. Anyone who has experienced mild spots will know that a pimple can form in as little as 1 hour, but that is just what we see on the surface of the skin. It is estimated that acne pathogenesis begins at least 12 hours before a visible spot on the surface of the skin appears.
The spot can persist on the skin for days or weeks, depending on its type (listed below). More severe forms of acne take longer to heal due to the extend of the lesion. Papules may heal within a day, whereas cysts may haunt your skin for over a week.
The more severe forms of acne vulgaris also leave behind scarring if the tissues beneath the skin become ruptured. These will heal over time, but it may take months, even years for their appearance to fade.
what can clog pores?
- Excess Sebum.
- Bacteria (Cutibacterium Acnes).
- Dead skin cells.
- Thickened inner lining of hair follicles.
- Dirt/excess product.
- Makeup/skincare products.
Causes of Acne
Changes in Endocrine Systems
Androgens (e.g., testosterone) are hormones which stimulate the production of sebum in the sebaceous glands. The influx of this oily substance may cause the pores on the face, back and chest to not drain properly, leading to pores becoming blocked and causing it to swell.
This is why we observe most cases of acne in adolescents as this is when hormonal changes are the most drastic; during puberty. Young men are likely to experience chronic effects of this skin condition as their testosterone levels rise and stay high. Young women may experience periods of larger outbreaks 14 days before their period, as that’s when androgenic levels are at their peak.
Women undergoing menopause may also experience acne due to the changes in testosterone and oestrogen levels.
Changes in skin microbiome
Each one of us has a unique microbiome, and it’s very important for our skin health. The commensal bacteria Cutibacterium acnes plays a key role in acne. Studies show that there is no significant differences in numbers of c.acnes on patients with acne skin and patients with healthy skin, however, patients suffering with acne had different strains of the bacteria, which could lead to the development of acne.
The skin microbiome can be affected by a wide variety of factors including: early life exposure, the environment, cosmetics, and anti-microbial agents.
Hyperkeratinisation (Retention Hyperkeratosis)
Retention hyperkeratosis is a phenomenon where corneocytes become cohesive, preventing them from shedding normally. This creates a slight thickening of the skin, which can clog pores, creating a build up of sebum under the skin.
Exposure to dirt / Skin irritation
Being exposed to dust, dirt, pollution and comedogenic (pore-blocking) products, increases your chances of developing acne. These fine particles sit on the surface of the skin which blocks pores, and builds up sebum inside the pore.
Your skin can also become irritated by external factors such as friction from tight clothing, exfoliating agents, or excessive touching of the face, leading to acne flare-ups. Many people experienced this during covid, famously known as maskne.
Types of Acne lesions
Inflammatory Acne
Papules
Small red bumps found just underneath the surface of the skin, without a defined centre. These spots are hard, raised and tender with slightly swollen, red skin surrounding it.
What you think of when we say spots.
- Colour: Red.
- Size: Very small.
- Characteristic: Just below the surface of the skin.
Pustules
Pustules have a defined centre and tend to be slightly larger. The centre contains a white-yellow puss filled with immune-system cells and bacteria.
Similar to papules, but have a white tip containing pus, look a little like inflamed whiteheads
- Colour: Red with a white tip.
- Size: Small.
- Characteristic: Small white tip filled with some puss.
Nodules
Large hard lumps, usually painful and inflamed, deep underneath the skin. Nodules form when the clogged pores damage surrounding tissue. They can create acne scars.
What we think of when we say acne.
- Colour: Pink/skin colour.
- Size: Large.
- Characteristic: Sub-dermal and painful.
Cysts
Large pus-filled soft lumps, found in the deeper layers of the skin, even deeper than nodules – and can cause severe scarring.
These carry the greatest risk of scarring, which needs to be treated.
- Colour: Pink/skin colour
- Size: Very large.
- Characteristic: Sub-dermal, painful and causes scarring.
Non-inflammatory acne
Black heads
Open pores filled with sebum and dead skin cells that have become oxidised, giving it a black appearance.
Small black/dark brown or yellow bumps. Typically found on the nose.
- Colour: Deep brown/black.
- Size: Very small.
- Characteristic: Tiny dark spots found around the nose.
White Heads
Very similar to blackheads, filled with sebum and dead skin cells, however, they are not open, instead, there is a thin layer of skin covering it. They are firmer than black heads and will not empty when squeezed.
- Colour: Lighter than skin colour.
- Size: Very small.
- Characteristic: Tiny sub-dermal spots, no visible redness.
Acne Categories
Acne Fulminans
- Demographic: White males aged 13-22.
- Cause: Elevated levels of testosterone.
- Symptoms: Painful clinical spots, polyarthritis & fever.
Elevated levels of testosterone may have a role in the pathogenesis of acne fulminans. Anabolic steroids are known to increase levels of sebum and density of Cutibacterium acnes. Bodybuilders who use anabolic steroids develop acne fulminans within a very short time.
Acne Excoriée
- Demographic: Girls and young women 13-22.
- Cause: Picking, scratching, or rubbing of acne sessions.
- Symptoms: Scabs and scars.
Acne excoriée, also known as “picker’s acne,” is a result of acne lesions being repeatedly picked, scratched, or rubbed, resulting in scabs and scars. It is seen most commonly in adolescent girls and young women, and it is sometimes associated with mental health disorders such as anxiety, depression, and obsessive-compulsive disorder.
Post-Adolescent Acne
- Demographic: Women 25+.
- Cause: Hyperandrogenism (overproduction of testosterone).
- Symptoms: Acne flare-ups around the lower face, jawline, and neck.
Post-adolescent acne is linked to the menstrual cycle. Mid-cycle, there is a spike in testosterone (an androgen), which up-regulates sebum production in the pilo-sebaceous unit, leading to clogged pores, and henceforth, spots. Papules do not last long (1 week), but can be a reoccurring issue.
Acne Mechanica/Pomade Acne
- Demographic: Not specific to gender or age.
- Cause: Comedogenesis due to chronic friction/occlusion from objects. or cosmetics.
- Symptoms: Acne flare-ups at the site of exposure.
Foreign objects (instruments, clothing, cosmetics) irritate/occlude the pilo-sebaceous unit which clogs pores. Typically temporary once the object of insult has been remove. Cosmetics may be comedogenic (pore-clogging), which prevents the natural excretion of sebum.
Prevention of Acne
Acne, in all of its forms, stems from a blockage of the pilo-sebaceous unit. These blockages typically stem from ‘comedogenic’ agents. These substances either sit on the surface of the skin or inside the pores, which leads to the insufficient dispersal of sebum across the surface of the skin.
When the sebum travels from the sebaceous glands through the sebaceous duct and up the follicular channel, it can not be excreted through the pore, therefore, it is forced to re-direct it’s flow back down into sebaceous unit, causing a build-up of sebum which leads to acne.
Avoiding comedogenic agents will help prevent acne formation.
examples of comedogenic agents
- Dirt, pollutants, bacteria.
- Sunscreen ingredients (avobenzone, oxybenzone, benzophenone).
- Long-chained hydrocarbon molecules (mineral oils and waxes).
- Makeup.
The extent of the comedogenic agent’s effects greatly depends on the length of time these substances remain on the skin. This is why cleansing (or even double cleansing) is so important. Surfactants emulsify impurities and dirt on the surface of the skin to make them easy to wash off with water.
Acne Treatments
Acne is a very complex skincare condition. As you have read above – there are four main causes of this skin condition, but there are so many factors which can contribute to each ’cause’, such as lifestyle choices, genetics and age.
The main skincare treatment for acne is the use of acids and retinoids. Both of these help to prevent the pores from clogging, and in some cases, even un-clog your pores.
The most common acne treatment for people experiencing mild spots is Salicylic Acid. This ingredient is a chemical exfoliant which breaks apart corneocytes from the epidermis by degrading desmosomes (molecules holding the corneocytes together).
