Recent findings in the epidemiologic evidence, classification, and subtypes of acne vulgaris.

Acne affects between 40 to 50 million individuals in the United States. Recent findings regarding the multifactorial pathogenesis of acne have facilitated a reexamination of the classification of acne and acne-related disorders. Disorders without a microcomedo as the initial pathologic condition are no longer classified as "acne." Research has also identified that the clinical characteristics of acne vary with age, pubertal status, gender, and race. These findings may have implications for the clinical management of acne and acne-related disorders.