Home Page
Health Care Providers Section

E-mail this page   Printable View

Acne Vulgaris

Acne is the most common skin disorder in the United States, affecting more than 17 million Americans. Most adolescents in Western countries experience some degree of acne, which generally resolves as androgen levels decline. Some cases, however, persist into adulthood or have their onset in adulthood.

Common acne, as it appears in adolescents, is associated with many factors, including genetic predisposition, hormonal abnormalities, and clogged pilosebaceous follicles. Plugs found in follicles of patients with acne are composed of a mixture of lipids secreted by sebaceous glands and keratin that accumulates from surrounding keratinocytes.

Acne may appear as closed comedones (“whiteheads”) or, when excessive distention forces open the follicular orifice, open comedones (“blackheads”). Oxidation of the lipid and melanin cause the darkened appearance of open comedones. Increased production of androgens during puberty leads to sebaceous gland growth and increased sebum production, providing an anaerobic lipid–rich medium that is optimal for bacterial growth. Propionibacterium acnes (an anaerobic diptheroid) proliferates and can incite an inflammatory reaction that results in the characteristic acne lesions.

Acne most commonly affects areas of the body with the greatest number of sebaceous glands. These include the face, upper back, neck, chest, and upper arms. Mild acne is not inflammatory and involves only a small number of open or closed comedones. Moderate–to–severe acne involves inflammation of the dermis surrounding the pilosebaceous unit. This inflammation is due to follicular rupture, spilling of free fatty acids (resulting from the hydrolysis of triglycerides by P. acnes), and the release of lysosomal enzymes from neutrophils attracted by chemotactic factors released by P. acnes. This process results in the formation of pustules, papules, or nodules that cover a large area of skin. Scarring and hyperpigmentation can also occur, usually in patients with darker complexions.

 

Next:
Acne Vulgaris: Risk Factors and Diagnosis >>