Emmy M. Fernandez, Andrea L. Zaenglein, and Diane M. Thiboutot
Department of Dermatology, Pennsylvania State University Milton S. Hershey Medical Center, Hershey Pennsylvania, U. S.A.
Acne is an exceedingly common condition affecting millions of adolescents and young adults. Not surprisingly, the psychological and economic impact of acne is reflected in these vast numbers. The prevalence in teenage girls ranges from 16-80%, while teenage boys are even more likely to be affected with prevalence ranging from 29-90% (1-4). These large variations in prevalence are due to differences in acne grading scales used in the various studies. Adult acne, although less common than adolescent acne, continues to be a significant problem for 3-6% of adult men, and 5-12% of adult women well into their thirties and forties (5,6). With so many persons affected, the economic impact of acne is immense. In 1999 there were approximately 35 million Americans with acne generating 7.9 million physician visits. That same year approximately 1.2 billion dollars was spent on prescription acne medications (7).
In addition to the economic impact, acne also has a significant psychological impact in both adolescents and adults. Thirty to fifty percent of adolescents experience psychiatric disturbances due to acne (8). Studies have shown that acne causes similar levels of social, psychological, and emotional impairment as asthma and epilepsy (9). Studies have also shown that unemployment is higher among adults with acne than among adults without acne (10).
In order to implement effective treatment strategies for patients with acne, a solid understanding of the physiology of the pilosebaceous unit and the pathological events that lead to acne are essential. The pathogenesis of acne is very complex, but four basic steps have been identified. These key elements (Fig. 1) are: (i) follicular epidermal hyperproliferation, (ii) excess sebum production, (iii) inflammation, and (iv) the presence and activity of Propionibacterium acnes (P. acnes).