ANSWER:
Eczema
Eczema (often used synonymously with dermatitis) refers to a variety of skin conditions characterised by epidermal inflammation and itching. The areas of skin affected vary in the different types of eczema, but the skin lesions share certain common features. In acute eczema the skin is typically red and inflamed with papules, vesicles, and blisters. In chronic eczema the skin may show the same features but be more dry, scaly, pigmented, and thickened. Eczema may be categorised as exogenous (including allergic, irritant, and photosensitivity eczema) or endogenous (such as atopic, discoid/nummular, gravitational, and seborrhoeic eczema), but there may be multiple causes of eczema, both endogenous and exogenous, in an individual patient. Two of the most common forms of eczema are atopic eczema and seborrhoeic dermatitis ().

Atopic eczema predominantly affects infants and children although adults may also suffer. The skin is itchy and there is a chronic or relapsing dermatitis in which the face and neck and flexures of the elbows and knees are involved most often and are excoriated and lichenified.

General principles for the management of atopic eczema may also be applied to other eczematous skin disorders. Cure of atopic eczema is said to be unrealistic, but good control can be achieved with proper management. The objective of treatment should be to reduce signs and symptoms, to prevent or reduce recurrences, and to provide long-term management by preventing exacerbation. Guidelines have been issued by the Primary Care Dermatology Society with the British Association of Dermatologists1 and by the International Consensus Conference on Atopic Dermatitis (ICCAD II).2 The management of eczema has also been reviewed.3

First-line treatment.

Regular bathing using soap substitutes is important to cleanse and hydrate the skin; soaps and detergents should be avoided as these remove the natural lipid from the skin. Suitable bath oils should be used to maintain skin hydration. Emollients should be applied liberally to the whole body at least twice daily, especially after bathing, and more frequently throughout the day to hands and face.

Patients should be educated on the avoidance of trigger factors. These may include irritants, microbes, and psychological or allergic factors.

Acute control of pruritus and inflammation.

Intermittent topical corticosteroids are the mainstay of treatment and are used for up to a week to manage acute flares of atopic eczema. Treatment for up to 6 weeks may be needed for initial control of chronic eczema. To minimise potential side-effects the minimum strength preparation to control the disease should be used, and the age of patient, site of eczema, and extent of disease should be considered when selecting the appropriate preparation. Very potent preparations should be used in children only under specialist supervision.

Topical calcineurin inhibitors (pimecrolimus or tacrolimus) may be used as alternative therapy. Pimecrolimus is indicated for mild to moderate disease and tacrolimus for moderate to severe eczema. The main side-effect is burning at the site of application. Once the condition settles the patient should revert to treatment with emollients.

Maintenance therapy.

For persistent disease or frequent flares, topical calcineurin inhibitors are effective and should be used at the earliest sign of recurrence. While these drugs prevent disease progression they do not have the adverse effects of corticosteroids and consequently may be used on all body areas (including sensitive areas like the face, eyelids, and neck) for extended periods. Studies so far suggest that these new drugs are safe in the short term. However, they do suppress T lymphocytes and although systemic absorption is minimal there may be a possibility of immunosuppression, skin cancers, or bacterial infection.

Topical corticosteroids may be used intermittently for acute exacerbations. Once the patient is back in remission emollients should be continued.

Coal tar preparations may be used occasionally for chronic atopic eczema, and ichthammol may be used as an ointment or paste bandages for chronic lichenified eczema.

Adjunctive therapy.

Overt bacterial, fungal, or viral infections should be treated with an appropriate systemic drug (see Skin Infections under Antibacterials, , and under Antifungals, ). Topical preparations are generally not used as they should be restricted to limited areas and patients with eczema often have widespread infections.

A sedating antihistamine may be used short term for severe pruritus associated with relapse or at night-time if scratching disturbs sleep or occurs while asleep. Non-sedating antihistamines are generally ineffective in eczema but may be of benefit in atopic dermatitis and concomitant urticaria.

Patients whose eczema fails to respond to these first-line treatments, even under specialist supervision, require further measures.

Severe refractory disease.

Phototherapy with ultraviolet A or B, or in combination, may be useful, and phototherapy using a psoralen (generally methoxsalen) with ultraviolet A (PUVA) may be used in severe, widespread disease. However, potential long term effects such as premature ageing of the skin and skin malignancy need to be considered.

Therapy with more potent topical and oral corticosteroids may be considered for short periods of time. In general, only mild corticosteroids (such as 1% hydrocortisone) should be used on the face and in flexures as absorption is increased in these areas.

Various other drugs have been tried in resistant eczema. Azathioprine, ciclosporin, or methotrexate may be tried in selected patients. Systemic corticosteroids are rarely indicated.

Evening primrose oil and borage oil have also been tried although evidence in favour of a useful therapeutic effect is poor. Other drugs at an experimental stage include interferons, mycophenolate mofetil, and thymopentin. There has been much interest in the use of complementary and alternative therapies and herbal medicines, but serious adverse effects have occasionally occurred and although encouraging results have been reported the degree of benefit is still uncertain.4,5

For further information on the substances mentioned above, see:

Antibacterials,
Antihistamines,
Azathioprine,
Borage Oil,
Coal Tar,
Corticosteroids,
Ciclosporin,
Evening Primrose Oil,
Hydrocortisone,
Ichthammol,
Interferon Gamma,
Methotrexate,
Methoxsalen,
Mycophenolate,
Pimecrolimus,
Tacrolimus,
Thymopentin (see Thymus Hormones, )