• A person with acne usually presents with a history of troublesome 'spots', most commonly affecting the face, shoulders, back, and chest. The person is most commonly an adolescent or young adult, but acne can occur for the first time in later life.
• Examine all affected areas of skin (including the back and shoulders).
• The skin and hair may have an oily texture and appearance.
• Depending on the severity of the acne, there may be non-inflammatory comedones, inflamed papules or pustules, or a mixture of both.
• Closed comedones (whiteheads) appear as raised bumps on the skins surface, and are skin-coloured or slightly reddened.
• Open comedones (blackheads) have a characteristic black 'plug' caused by oxidised oil and dead skin cells.
• Papules are small, round or oval, inflamed (red), raised elevations of the skin.
• Pustules resemble papules, but have a central pocket of pus.
• Nodules are poorly demarcated swellings that are usually red and tender. They may be fluctuant on palpation. In very severe acne, nodules may track together and form large, deep sinuses (acne conglobata).
• Haemorrhagic acne is caused by bleeding inflammatory lesions, and may be very painful and distressing.
• Look for evidence of scarring and hyperpigmentation.
• Scarring may occur when acne heals, particularly when nodules have been present. It is most commonly atrophic in nature, leading to the formation of 'ice-pick' scars or 'pock marks'.
• Hyperpigmentation may occur after acne resolves, especially in people with darker complexions.
• If the features are atypical of acne vulgaris, consider the possibility of a severe form or clinical variant of acne.
• Images of acne and its clinical variants can be viewed at www.dermnet.org.nz.

[Brown and Shalita, 1998; Thiboutot, 2000; Simpson and Cunliffe, 2004; ICSI, 2006]