Acne Vulgaris

Acne vulgaris (acne) is an extremely common condition, often affecting people during puberty and adolescence. Most people are affected at some point during their lives, and symptoms can range from mild to severe.

 

Pathophysiology

Acne is caused by chronic inflammation, with or without localised infection, in pockets within the skin known as the pilosebaceous unit. The pilosebaceous units are the tiny dimples in the skin that contain the hair follicles and sebaceous glands. The sebaceous glands produce the natural skin oils and a waxy substance known as sebum.

Acne results from increased production of sebum, trapping of keratin (dead skin cells) and blockage of the pilosebaceous unit. This leads to swelling and inflammation in the pilosebaceous unit. Androgenic hormones increase the production of sebum, which is why acne is exacerbated by puberty and improves with anti-androgenic hormonal contraception. Swollen and inflamed units are called comedones.

The Propionibacterium acnes bacteria is felt to play an important role in acne. This is a bacteria that colonises the skin. It is thought that excessive growth of this bacteria can exacerbate acne. Many of the treatments of acne aim to reduce these bacteria.

 

Presentation

There is significant variation in the severity of acne. It presents with red, inflamed and sore “spots” on the skin, typically distributed across the face, upper chest and upper back.

There are few terms used to describe the appearance of the lesions:

  • Macules are flat marks on the skin
  • Papules are small lumps on the skin
  • Pustules are small lumps containing yellow pus
  • Comedomes are skin coloured papules representing blocked pilosebaceous units
  • Blackheads are open comedones with black pigmentation in the centre
  • Ice pick scars are small indentations in the skin that remain after acne lesions heal
  • Hypertrophic scars are small lumps in the skin that remain after acne lesions heal
  • Rolling scars are irregular wave-like irregularities of the skin that remain after acne lesions heal

 

Management

The aim of treatment is to reduce the symptoms of acne, reduce the risk of scarring and minimise the psychosocial impact of the condition. Always explore the psychosocial burden and any potential anxiety and depression that may be associated with the condition.

Treatment is initiated in a stepwise fashion based on the severity and response to treatment:

  • No treatment may be acceptable if mild
  • Topical benzoyl peroxide reduces inflammation, helps unblock the skin and is toxic to the P. acnes bacteria
  • Topical retinoids (chemicals related to vitamin A) slow the production of sebum (women of childbearing age need effective contraception)
  • Topical antibiotics such as clindamycin (prescribed with benzoyl peroxide to reduce bacterial resistance)
  • Oral antibiotics such as lymecycline
  • Oral contraceptive pill can help female patients stabilise their hormones and slow the production of sebum

Oral retinoids for severe acne (i.e. isotretinoin) is an effective last-line option, although it is only prescribed by a specialist after other methods fail. This needs careful follow-up and monitoring and reliable contraception in females. Retinoids are highly teratogenic.

Co-cyprindiol (Dianette) is the most effective combined contraceptive pill for acne due to it’s anti-androgen effects. It has a higher risk of thromboembolism, so treatment is usually discontinued once acne is controlled and it is not prescribed long term.

 

Isotretinoin

Oral isotretinoin (Roaccutane) is very effective at clearing the skin. It is a retinoid, and works by reducing production of sebum, reducing inflammation and reducing bacterial growth. It can only be prescribed under expert supervision by a dermatologist. It is strongly teratogenic (harmful to the fetus during pregnancy). Patients need to have effective and reliable contraception and must stop isotretinoin for at least a month before becoming pregnant.

 

Side effects of isotretinoin include:

  • Dry skin and lips
  • Photosensitivity of the skin to sunlight
  • Depression, anxiety, aggression and suicidal ideation. Patients should be screened for mental health issues prior to starting treatment.
  • Rarely Stevens-Johnson syndrome and toxic epidermal necrolysis

 

Last updated January 2020
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