Introduction to acne

Acne is a chronic inflammatory disease of the pilosebaceous unit. It is common in adolescents and young adults, and is more severe in males. Onset peaks early in puberty, and usually resolves in males during their early twenties. Females are more likely to have ongoing acne persisting into their thirties and forties. Acne can also occur in infants; see Infantile acne.

Acne only occurs in the presence of androgens. It is usually caused by increased sensitivity of the pilosebaceous unit to circulating androgens—it is rarely due to increased androgen concentrations. Skin changes in acne usually include:

• increased sebum production induced by the action of androgens on the pilosebaceous unit
• hypercornification of the pilosebaceous duct, with formation of keratin plugs
• colonisation of more virulent strains of Cutibacterium acnes (formerly Propionibacterium acnes)Platsidaki, 2018
• inflammation.

Acne mainly affects areas with the highest density of sebaceous glands (eg face, neck, chest, shoulders, upper back).

For information on diagnosis and classification of acne (including different types of acne lesions and severity categories), see here.

When treating a patient with acne, explain that it is a chronic condition, and manage the patient’s expectations of a cure. Also be sensitive to the profound negative emotional and social effects acne can have on the patient. In some patients, acne can lead to social withdrawal, preoccupation with the acne, distorted body image, low self-confidence and self-esteem, depression and suicide.