Acne Vulgaris

Etiology

Acne vulgaris (or acne) is a chronic inflammatory disorder that affects areas with the greatest concentration of sebaceous glands, such as the face, chest, and back. Gender, age, genetic factors, and environment are all major contributing pathogenic factors. Stress may trigger acne, possibly by affecting hormone levels. A high glycemic diet and milk intake, low-fat/skim milk in particular, may be associated with acne, although they remain controversial as potential causes.

Acne is caused by chronic inflammation of the pilosebaceous unit (hair follicle with an associated sebaceous gland). The primary event in all acne lesions is the development of the microcomedo , which results from the obstruction of the hair follicle with keratin, increased sebum production from sebaceous glands, and overgrowth of normal skin flora, leading to pilosebaceous occlusion and enlargement. Androgens are a potent stimulus of the sebaceous gland. The subsequent inflammatory component and pustule formation results from proliferation of Cutibacterium acnes (formerly Propionibacterium acnes ), a commensal organism of the skin. The pathogenesis of acne involves three components: increased sebum production, hyperkeratosis, and bacterial proliferation. Effective treatment focuses on minimizing these factors.

Epidemiology

Acne is the most common skin disorder in adolescents, occurring in 85% of teenagers. The incidence is similar in both sexes, although boys often are more severely affected. Acne may begin as early as 6–8 years of age and may continue into adulthood.