Definition

Acne is an integumentary disorder that affects the pilosebaceous units (acne vulgaris) and/or the underlying blood vessels (rosacea) of the skin. Some of the variants of the disease include acne vulgaris, acne conglobata, acne fulminans, acne excorié, mature onset, pyoderma faciale, rosacea, neonatal and infantile acne.

Epidemiology

Males and females of all ages can be affected by acne;¹ however, the type of acne can vary between sexes. The vulgaris, conglobata and fulminant variants of acne, for example, are most prevalent among adolescent males, while acne excorié, rosacea, mature onset and pyoderma faciale are more likely to manifest in women.¹

Aetiology and pathophysiology

Many factors can be implicated in the pathogenesis of acne, including genetic, hormonal, infectious, dietary and environmental elements. In terms of hormonal influence, it is believed that elevated androgen levels increase sebum production and abnormal follicular keratinisation and desquamation, which leads to the blockage of pilosebaceous units and the formation of comedones.¹ The peak elevation in androgen, sebum and growth hormone levels during the adolescent period provides some explanation for the increased prevalence of this condition during adolescence.² Findings from a case study of 34 men and women with acne adds further support to the relationship between androgen levels and acne lesion count.²

The bacterium Propionibacterium acnes is another contributing factor in acne development. This is because the bacterium promotes inflammation by releasing chemotactic factors and proteases while hydrolysing sebum into proinflammatory free fatty acids.^1,3 In rosacea, an underlying vascular defect may be responsible,³ although the actual aetiology of this disorder remains unclear. What is apparent is that rosacea can be triggered by a range of exogenous and endogenous stimuli, including cold or hot weather, wind, sun exposure, exercise, hot baths, emotional stress, alcohol, spicy foods, cosmetics and hot drinks.⁴

Other environmental factors that may be implicated in the pathogenesis of acne include medications (e.g. steroids, anticonvulsants), occlusive objects (e.g. shirt collars, helmets), topical agents (e.g. cosmetics, lotions, creams) and perspiration.^4,5

The chronic consumption of foods with a high glycaemic index or glycaemic load also contributes to acne development by promoting hyperinsulinaemia and insulin resistance. This can be followed by elevated free levels of insulin growth factor and androgens, and a subsequent rise in keratinocyte proliferation, sebum production and acne formation.⁶

Clinical manifestations

Acne can range in severity from mild to severe. In mild cases, acneiform lesions might be limited to open (blackheads) and closed (whiteheads) comedones, and papules. In more severe cases, inflamed papules, pustules, nodules and cysts may develop, which can lead to scarring.^1,3 The presence of these lesions, as well as scarring, can impact negatively on the psychological wellbeing of the client and their family. Systemic manifestations of the disease can also present in certain variants, such as acne fulminans, with symptoms that include pyrexia, malaise, arthralgia and weight loss.³ In most cases, acneiform lesions are confined to the face, upper back and chest where pilosebaceous units are most abundant. In rosacea, lesions are generally localised to the face and are often accompanied by facial erythema, oedema and telangiectasia.⁵