Acne is a disorder affecting the pilosebaceous unit associated with excess grease production of the skin, keratinization of the opening of the hair follicle, and inflammation due to bacterial infection with Propionibacterium acnes that may result in scarring.

Acne typically presents with open comedones (black heads), closed comedones (white heads), papules, pustules, and cystic lesions (6.3). The face, upper chest, and upper back are most commonly affected. Macrocomedones and scarring (both pitted and hypertrophic) are also features. A particular variant, acne excoriée, is characterized by marked excoriations on the face and is typically seen in young women (6.4).

Perifollicular inflammation with a predominance of neutrophils is seen. The hair follicles are often dilated, and filled with keratin. Rupture of the follicles can result in a foreign body reaction.

Folliculitis, rosacea, and perioral dermatitis can all mimic acne on the face. Acne-like conditions can also be precipitated by drugs (e.g. antiepileptics), topical and oral corticosteroids, oils applied to the hair line (pomade acne), and exposure to various chemicals (e.g. chloracne).

Most acne will clear spontaneously by the mid twenties. Mild acne can be managed by topical agents, applied daily for 3-6 months. These include benzoyl peroxide (first line, good for noninflammatory acne), topical antibiotics (erythromycin, clindamycin), and topical retinoid related drugs (tretinoin and adapalene). Combinations of these agents can also be used, for example benzoyl peroxide in the morning and a retinoid in the evening.

Moderate acne is best managed with systemic antibiotics in addition to topical agents. These again require 3-6 months of treatment to achieve long-term clearance. These include oxytetracycline, lymecycline, erythromycin, and trimethoprim.

For unresponsive cases or severe acne associated with scarring, specialist referral is indicated. Such patients may require a 4-6 month course of oral isotretinoin. This achieves clearance in 85% of patients. Frequent side-effects include dryness of the lips, mucous membranes, and skin. It should be avoided in pregnancy and patients may require monitoring of their liver function and lipids. Any change in mood or tendency to depression during treatment should lead to cessation of therapy.

Perioral dermatitis typically affects young women in the 20-35-year-old age group. It is a variant of rosacea and may be precipitated by inappropriate use of moderate/potent topical corticosteroids.

It is characterized by small erythematous papules around the mouth and chin (6.5A). The area immediately adjacent to the vermillion border is usually spared. There may also be periorbital involvement. Comedones are not a feature.

Acne vulgaris, steroid acne, rosacea, and seborrhoeic dermatitis are the main differentials.

Patients should be advised to stop the application of topical corticosteroids and placed on a 2-4 month course of oral tetracycline antibiotics (6.5B). Topical tacrolimus and pimecrolimus may also be beneficial for flares.

Rosacea is a common cause of facial redness in the 25-55-year-old age group, especially women.

Many patients have a history of flushing exacerbated by trigger factors including spicy foods, temperature changes, and alcohol. Facial redness typically occurs with small papules and occasional pustules (6.6, 6.7). The inflammatory changes typically affect the cheeks and nasolabial folds. Fixed redness may develop associated with superficial blood vessels (telangiectasia) and rarely sebaceous hyperplasia leads to an enlarged nose (rhinophyma) (6.8). Up to 15% of patients may have associated eye involvement presenting as conjunctivitis, keratitis, blepharitis, and cyst formation along the eyelid margin. Comedones are typically absent in rosacea.

A mixed lympho-histiocytic perifollicular infiltrate may be present. In addition, there may be a perivascular infiltrate or granulomatous response. These changes are nonspecific. There may also be vascular dilatation, solar elastosis, and sebaceous gland hyperplasia indicating solar damage.

Rosacea should always be suspected in patients with facial redness and papules. Other causes of flushing and erythema include eczema, seborrhoeic dermatitis, systemic lupus erythematosus, and the carcinoid syndrome.

Patients should avoid trigger factors. Mild cases can be managed with topical metronidazole gel. More severe cases (6.7) require courses of systemic tetracyclines for 2-4 months. Many patients experience disease relapses and patients should be informed that it might be a chronic condition. Severe cases may need a specialist opinion and low-dose oral isotretinoin can be beneficial. Patients with rhinophyma and telangiectasia may benefit from skin surgery and laser therapy, respectively.

Facial eczema commonly affects adults with severe eczema and can be a presenting feature of allergic contact dermatitis.

In infants the cheeks are a common site to be involved, with an ill-defined, red, scaling rash that is symmetrical. Episodes of infection are common and weeping and crusting are both common in this context. In adults, eczema can be either generalized (6.9, 6.10), or more localized to specific areas such as the skin around the eyes and mouth. Lichenification of the skin may be present around the eyes (6.11).