The use of the term ‘acne’ for the condition we know by that name has had a curious and complicated history.

It is one of the most frequently seen chronic skin diseases and is the commonest dermatological disorder of adolescents.

Acne is a disease affecting the pilose-baceous follicles, particularly on the face and the upper trunk, in which there are four major aetiological factors: increased sebum production, hypercornification of the pilosebaceous duct, abnormal bacterial function and production of inflammation. The seborrhoea, which is androgen mediated, may, in a small number of patients, be due to an increase in circulating androgens but in most cases it is much more likely to be an end-organ hyperresponse of the sebaceous glands to normal hormonal levels.

The mechanisms producing hypercornification are uncertain: this too may be an abnormal response to the duct to androgens; it may also be due to abnormality in the sebaceous lipid resulting in a retentive hyperproliferation of the corneocytes. Certain bacteria, in particular Propionibacterium antes, colonize this duct and produce many biologically active substances which could, along with products arising from the cornified and intercellular material, escape into the surrounding dermis, stimulating chemotaxis, complement activation and the production of inflamed lesions.

The reason why acne resolves in the mid-twenties or sometimes later is simply not known. It is not related to a marked reduction in sebum excretion nor a change in lipid composition. The clinical presentation of acne rarely offers any problem to the physician or even to the patient. Acne vulgaris is the commonest form of acne but there are many uncommon subgroups. These may represent severe variants such as acne fulminans, pyoderma faciale, and acne conglobata.

There are also many unusual types of acne, including infantile acne, cosmetic acne and pomade acne. Even though the precise mechanisms of acne are unknown its treatment is relatively straightforward. Most patients should respond well, 92 per cent showing an 80 per cent response in six months. Patients with mild acne usually require topical therapy; those with more severe acne would receive oral therapy in addi-tion.

The commonest oral therapies are antibiotics, in particular, tetracycline. Those patients who do not do well may be considered for hormonal therapy such as Dianette, spironolactone or, in the most severe and recalcitrant cases, isotretinoin. The last drug is a guaranteed success; it does, in contrast to other acne therapies, have many side-effects but these’ are well tolerated by virtually all patients. Although scarring is a common feature in some acne patients, the availability of early treatment should dramatically reduce its incidence.