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The changing faces of acne

Acne is one of the most common skin complaints in the world. It can affect people of all ages, but it is most common in prepubescent teenagers. Acne tends to be more prevalent, and more severe, in male teenagers, but more frequent and persistent in the adult female population. More and more is now understood about the exact causes of acne, and among them, hormones, diet, lifestyle and genetic factors are thought to play roles. The spectrum of acne is broad, and presentation varies from mild acne (small collections of comedones with a small proportion of papules and pustules) to moderate acne (larger numbers of lesions with a greater proportion of papules and pustules) and even to severe acne (where, in addition to large numbers of papules and pustules, large, painful nodules and cysts are also present). While acne is most common on the face, lesions may also be found on the forehead, chest, upper back and deltoid areas. Severe acne on the upper back and chest can be aggravated by sweating during exercise and by the wearing of overly tight clothing. Three distinct but closely interrelated processes are believed to play critical roles in the formation of acne lesions: (i) alteration of the keratinization process of the wall of the pilosebaceous follicle, leading to comedo formation; (ii) increased sebum production with modification of its composition; and (iii) follicular colonization by Propionibacterium acnes, secreting inflammatory mediators around pilosebaceous units and activating the skin’s innate immunity. Although the exact sequence of events resulting in acne remains to be fully elucidated, more is understood about the progression from mild to more severe forms of acne, which is dependent on sebum production and colonization of open and closed comedones (blackheads and whiteheads, respectively) by P. acnes. It is the body’s immune response to the presence of the bacteria that leads to inflammation and the formation of papules, pustules and cysts – which, in the most severe forms, may be associated with pain and disfigurement. Recently, a number of novel concepts for acne physiopathology have been proposed based on new research and approaches, providing new avenues of research to elucidate this complex disease fully. The physical effects of moderate and severe acne can persist even after the lesions themselves have healed. A large proportion of these patients develop persistent erythema, postinflammatory hyperpigmentation (PIH) and/or scarring, yet their impact is often underestimated. It can be many months before melanin in the dermis from PIH is removed, giving the appearance of persistent acne in some patients. Scarring is caused by disruption of the skin structure during the disease process and/or by overproduction of collagen following the production of inflammatory cytokines as a result of the immune response. Without treatment, these scars will be permanent. For reasons that are not fully understood, PIH and scarring are more prevalent in darker skin types, and there are reports that suggest that, in these patient groups, this is not restricted to severe forms of acne. Timely treatment to control P. acnes and inflammation therefore is particularly important in this patient population. In addition to the physical impact of acne and its sequelae, evidence shows that they can have a profound emotional and psychological impact on patients regardless of the severity of acne. Therefore, a strong relationship of trust between healthcare professionals and patients is needed in order to treat acne effectively. Acne has recently been recognized as a chronic disease, and experts agree that it should be managed as such. The choice of topical treatments for acne varies according to the type and severity of the lesions, and currently includes topical benzoyl peroxide and retinoids. Topical antibiotics remain the most commonly prescribed treatment for acne, in spite of international guidelines discouraging their use due to the induction of bacterial resistance. The most frequent systemic treatments that are prescribed for acne are tetracyclines, hormonal treatment for female patients and isotretinoin. Dermocosmetics may also have an important synergistic effect when combined with acne treatments. However, it is generally acknowledged that there remains a lack of new treatment options available at present. Early intervention with appropriate, effective treatment is important to reduce the inflammatory response and prevent the development of scars. Preventing the progression of comedones to inflamed acne lesions is the best way to prevent the development of PIH and scarring, and to ameliorate the emotional burden on patients. On 6 June 2014, a group of experts met to discuss ‘The Changing Faces of Acne’ with an international audience of dermatologists. This supplement, commissioned by Av ene Dermatological Laboratories, brings together the content of the presentations for the dermatology community. In seven papers by renowned experts in the field, the current acne landscape is examined and discussed. Firstly, Jerry Tan takes a global perspective on the epidemiology of acne, the eighth most prevalent disease worldwide. He highlights the need to develop a universal assessment scale to improve the evaluation of research results in epidemiological studies. Dae Hun Suh then looks at new developments in the physiopathology of acne, including new and exciting