ACNE
DEFINITION
Acne vulgaris is an inflammatory disease of the skin that affects those areas which contain the largest sebaceous glands, including the nose, central forehead, medial cheeks, medial chin, back, and trunk. Generally self-limiting, acne is characterised by comedones and inflammatory lesions such as papules, pustules and in more severe cases, cysts and nodules. Lesions are generally more severe and prevalent in males, but more persistent in females. Acne can present in neonates and infants, but the majority of cases occur in adolescents (an estimated 85% of those between 15-24 years of age are affected to some degree), typically resolving by age 30.
Rising androgen levels characteristic of adolescence are thought to increase the number of sebaceous glands and the amount of sebum they produce. The increased production of sebum causes blockage of hair follicles, leading to the formation of small cysts called comedones as well as proliferation of Propionibacterium acnes, an anaerobic gram positive diptheroid. Chemoattractants produced by this anaerobic organism promote the entrance of polymorphonuclear neutrophils into the affected area resulting in inflammation. P. acnes also hydrolyses triglycerides into free fatty acids which contribute to inflammation and follicular obstruction.
Aetiology / Risk Factors
Major causative factors and risk factors that can contribute to the incidence of acne include
- High insulin levels, associated with insulin resistance, are implicated in the development of acne, through the dual stimulation of epithelial cell proliferation and increased androgens, leading to an increase in sebum production. A high Glycaemic Load diet is therefore a risk factor.
- Fluctuating hormones associated with adolescence, menstruation (acne tends to flare 2 to 7 days pre-menstruation), or pregnancy.
- Acne patients of both genders have been found to have serum zinc levels on average 28.3% lower than control subjects. Hair levels were 24.3% lower and nail levels were 26.7% lower than controls. (Pohit J, et al. Zinc status of acne vulgaris patients. J App Nutr 1985;37(1):18-25).
- Genetic predisposition—particularly affects the severity of presentation
- Certain medications—corticosteroids used topically or in high oral doses; anabolic (androgenic) steroids; oral contraceptives; lithium, isoniazid, phenytoin and phenobarbitone may also cause eruptions. High levels of halogens such as iodine (from kelp, for example) may also lead to or exacerbate acne.
- Greasy/oily cosmetic or hair products containing vegetable or animal fats
- Environmental irritants such as industrial cutting oils, tar, wood preservatives, sealing compounds, and other pollutants
- Friction and sweating—for example, from headbands, back packs, bicycle helmets, or tight collars, can initiate or aggravate inflammatory acne lesions.
- Squeezing and picking comedones can worsen acne
SYMPTOMS & SIGNS
Common signs and symptoms of acne include:
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Open comedones ("blackheads") that contain easily expressed material. Blackheads are dark in appearance and resemble (but do not represent) dirt, and do not generally cause localised inflammation.
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Closed comedones ("whiteheads") that appear as 1 to 2 mm white papules and contain material that is not easily expressed
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Inflamed papules, pustules, or nodules
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Large cysts and nodules, which form in a small number of acne sufferers and may drain and leave scars
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Scarring, which may have several manifestations depending on both the skin type and the type and extent of acne. Scarring may manifest as small pits or "ice-pick" scars on the face and/or trunk; small or large atrophic and/or depressed scars; or hypertrophic scars (most often seen in those with darker skin colour).