Diagnosis and evaluation of acne.

The diagnosis of acne usually can be made on the basis of a history and physical examination. The differential diagnosis includes a variety of possible causes and differs according to age group (mid-childhood, 1-7 years of age; pre-, peri-, and early pubertal, 8-11 years of age; pubertal/postpubertal, >or=12 years of age). The presentation of acne in adolescents tends to include both noninflammatory and inflammatory lesions, whereas in younger patients noninflammatory comedones are typical. Keratosis pilaris affecting the cheeks sometimes may be confused with early acne vulgaris. Screening tests, particularly bone age, may be considered to support the clinical diagnosis in younger children. Further testing usually is not indicated unless patients show signs of virilization.