Dermatitis and its variantsDr Daniel HewittDermatologistSkin and Cancer Foundation Westmead
ObjectivesTo understand the basic pathology of dermatitisTo understand its main causes and precipitantsTo appreciate the different possible presentations and the effect on the patientTo list therapeutic optionsTo appreciate some of the variants of dermatitis
IntroductionDermatitis is extremely common in General Practice and Dermatology.There are many forms, of which atopic dermatitis is the most common.Patients and their families are greatly disturbed by the itch of dermatitis.Eczema and dermatitis are synonymous.Literally, dermatitis is “inflammation of the skin.”More specifically it is defined by a presentation of itchy, scaly and usually erythematous skin. Histologically, the hallmark is spongiosis or oedema in the epidermis – the keratinocytes in the epidermis are pushed apart by this fluid.
Atopic dermatitisAtopic dermatitis affects approximately 15% of children and this prevalence is increasing in Western societies.It presents in the first year of life in 60%The causes are complex and multifactorial.There is a genetic susceptibility – this predisposes to a defect of the epidermal barrier function. Patients lose the moisture in the skin more readily due to differences in proteins (especially filaggrin) in the epidermis.Subsequent immune stimulation and immune regulation lead to chronic inflammation and the itch and erythema of dermatitis.Patients may also have a tendency to form IgE antibodies and develop asthma and/or hayfever. However, atopic dermatitis is not primarily an allergic disease.
Clinical featuresAtopic dermatitis is a clinical diagnosisItching is usually the most troublesome symptom and may wake the patient at night.There is poorly defined erythema often with a dry, scaly skin. This is usually on the face in babies and spreads to the flexural surfaces most characteristically in older children.There may be weeping or crusting superimposed. Crusting may represent superimposed bacterial infection (impetiginisation.)Lichenification or thickening of the skin with accentuated skin lines can occur in more chronic cases.Excoriations (scratching induced areas of skin loss) are common.
TriggersAtopic dermatitis is essentially endogenous,but a number of triggers can flare the disease.These generally dry or irritate the skin – Soap, shampoo, bubble bath – Water itself, especially prolonged or frequent contact – Wool – Heat – Grass, sand – Citrus fruits – StressAllergies are possible but less common than irritants.
ManagementThis comprises two main aspects1 Controlling the inflammation2 Restoring the barrier with regular moisturisationThe management plan must be well understood by patients or their carers. The treating doctor must give detailed but clear explanations and ensure the plan is agreed to by the carers.Atopic dermatitis is a chronic disease with no cure. It can be controlled but a long-term management plan must be established.The psychosocial aspects of both the disease and the need for ongoing management are often profound.
Topical corticosteroids are essential in the management of acute dermatitis. Parents are often very concerned about possible side effects but when used appropriately they are very safe and effective.A topical steroid that is potent enough and appropriate for the site is to be used in the short term to settle the dermatitis. Face, nappy area, closed flexures (mild potency) – 1% hydrocortisone ointment – Desonide .05% lotion – More severe, betamethasone 0.02% ointment Widespread low grade disease (moderate potency) – Betamethasone 0.02% ointment – Triamcinolone 0.02% ointment More severe disease (more potent) – Methylprednisolone 0.1% ointment – Mometasone ointment Lichenified areas (more potent) – Mometasone ointment – Methylprednisolone fatty ointment – Betamethasone 0.05% diproprionate
Moisturisation is essential. There are many products and methods, but the regime must be acceptable to the patient.Bath oils and moisturising creams are most commonly used. More greasy preparations (eg “dermeze”) are generally better moisturisers but also less pleasant for patients to use.A typical regime would be QV bath oil in the bath QV soap free wash to wash skin – no soap or bubble bath to be used Gently pat dry after bath Apply QV cream all over in first few minutes after driedMoisturiser may need to be applied multiple times a day if the skin is very dry.
Irritant contact dermatitisThis is inflammation of the skin due to the effect of a drying or irritating influence on the skin. This effect accumulates over time and dermatitis results when the natural healing mechanisms of the skin are overcome by the repeated damage.It is most often seen in people who frequently wash their hands, such as housewives, hairdressers, mechanics.Those with atopic dermatitis are proneto this as adults.
Irritant contact dermatitis of the hands Irritant contact dermatitis due to saliva
Allergic contact dermatitisThis is due to a specific allergen that has contacted the skin and triggered a type IV delayed type hypersensitivity reaction.In can co-exist with both atopic dermatitis and irritant contact dermatitis.Some occupations, such as hairdressers, plumbers, carpenters and construction workers are particularly prone as they are exposed to both irritants and allergens.Patch tests are done to assess for allergic contact dermatitis. Panels of allergens are applied to the back and the patient is assessed for evidence of an allergic reaction
Discoid dermatitisThis is a clinical form of dermatitis in which there are well defined lesions.It can present in atopic dermatitis and often occurs in those with a generally dry skin.It can be quite resistent to treatment and often leaves some residual colour change in the skin (post-inflammatory hyperpigmentation.)
Asteatotic dermatitisPatients with very dry skin can develop this form of characteristic dermatitis. It has a “crazy-paving” appearance, due to cracks developing in the epidermis.It is particularly common in the elderly and is often seen in air- conditioned environments, such as hospitals, where the air is dry.
Venous stasis dermatitisThis is common in those with venous insufficiency. When the valves in the lower legs become faulty from previous thrombosis or chronic pressure on the venous system, excess fluid accumulates in the legs.The skin tissues become inflamed and itchy.There may also be scaling, weeping and ulceration.
Seborrheic dermatitisThis is a form that presents with ill-defined pink patches often with yellow or greasy scale.It is most common over the medial cheeks, eyebrows and forehead and can be associated with dandruff. It also occurs over the chest and in the groins and axillae.It has different causes and treatments to atopic dermatitis. There is a relation to the Malassezia yeast and it frequently flares with physical or psychological stresses.Treatment inculdes antifungal, anti-inflammatory and keratolytic preparations.
ConclusionDermatitis is the most common cause for an itchy skin eruption.Usually topical treatment is adequate, but sometimes patients require ultraviolet therapy or systemic therapy.There are many different causes and variants of dermatitis and these all have characteristic features.