Chapter: Medicine and surgery: Dermatology and soft tissues

Acne vulgaris - Facial dermatoses

Acne is a chronic inflammatory disease of the pilosebaceous units, which may result in comedones (black- or white-headed spots), papules, pustules, cysts and scars. - Definition, Incidence, Aetiology, Pathophysiology, Clinical features, Complications, Investigations, Management, Prognosis.

Facial dermatoses

 

Acne vulgaris

 

Definition

 

Acne is a chronic inflammatory disease of the pilosebaceous units, which may result in comedones (black- or white-headed spots), papules, pustules, cysts and scars.

 

Prevalence

 

Acne will affect approximately 85% of individuals at some time.

 

Age

 

Generally confined to adolescence but may persist.

 

Sex

 

= F (females affected earlier).

 

Aetiology/pathophysiology

 

The process of acne begins in the keratinocytes within the follicles of the pilosebaceous glands. Increased proliferation and reduced loss of keratinocytes increases their number and blocks the follicles with a hyperker-atotic plug (microcomedo).

Increased androgens around puberty and an increased sensitivity to androgens causes hyperplasia of the sebaceous glands and increase sebum production. Accumulation of the sebum in a follicle obstructed by hyperkeratosis creates a closed comedo or white-headed spot. Reopening of the follicle due to distension causes the formation of an open comedo, which appears as a blackhead.

 

Propionibacterium acnes, an anaerobic commensal of the skin, is able to grow in the anaerobic environment produced by the combination of increased sebum production and blockage of the follicular canals.

 

Rupture of a follicle into the dermis and/or the hydrolysis of lipids in the sebum by P. acnes results in an inflammatory reaction that may cause cysts, pustules, papules, and scarring.

 

Exacerbating factors include excess androgen production, oily creams and cosmetics, humidity and heavy sweating. Mechanical trauma such as excessive scrubbing increases inflammation and scarring. Diet does not affect sebum production or acne. Excess steroids, either endogenous or exogenous, can induce a pustular form of acne mainly affecting the back and shoulders. Infantile acne is a self-limiting condition seen in babies due to the effect of maternal androgens.

 

Clinical features

 

Lesions occur at sites where there are many sebaceous glands such as face, shoulders, back and upper chest. Scars may follow healing particularly when cysts have formed, leaving skin depressions, and may result in keloid formation.

 

Management

 

Local treatments include topical retinoids, which normalise keratinisation and prevent follicular blockage, benzoyl peroxide, a keratolytic agent, and topical antibiotics, such as tetracycline. These may be used in combination in more severe acne.

 

Systemic treatments are used for refractory acne or if scarring occurs:

 

Low-dose oral antibiotics such as erythromycin, tetra-cycline or trimethoprim may be used but need to be continued for up to 6 months.

 

Cyproterone acetate and ethinyl oestradiol, a combined oral contraceptive, also has an antiandrogen effect. It can be used in women eligible for oral contraceptives.

 

Oral retinoids are derivatives of vitamin A. They have an anti-inflammatory action and reduce sebum production for up to a year, this in turn causes a decrease in P. acnes due to reduced sebum. These are very effective with 80% of patients achieving long-term remission after a single course of treatment. However, retinoids are highly teratogenic causing spontaneous abortions and severe life-threatening congenital malformations. Women require a pregnancy test prior to starting therapy and should ideally use both an oral contraceptive and a barrier contraceptive during and for 1 month after treatment. Retinoids may rarely cause hepatitis, jaundice and pancreatitis. Patients require regular liver function tests and lipid profile measurement during treatment.

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Medicine and surgery: Dermatology and soft tissues : Acne vulgaris - Facial dermatoses |


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