Dermatitis, also called eczema, refers to superficial skin inflammation.
Acute lesions are red and swollen. Blisters may form which, on breakage, leak fluid leading to the formation of crusts. Subacute lesions are red or brownish with scaling. Chronic lesions are dry and leathery (lichenification).
There are many different forms of dermatitis but the symptoms and signs are similar. Itch (pruritus) is the most common symptom of dermatitis. Burning and/or pain may occur, but is uncommon. Itching leads to scratching. Scratching causes erosions (superficial loss of skin) and ulcerations (deeper loss of skin). The latter may lead to scarring.
Treatment is generally similar for all the different types of dermatitis.
The terms eczema and dermatitis are used interchangeably.
There are several different forms of dermatitis:
Allergic contact dermatitis
Chronic dermatitis of the hands and feet
Generalised exfoliative dermatitis
Localised scratch dermatitis or neurodermatitis
Each form will be dealt with separately.
Allergic contact dermatitis
Allergic contact dermatitis is an acute or chronic inflammation caused by skin contact with certain substances.
Itching (pruritus) is the main symptom.
Acute lesions are red and swollen. Blisters form and breakage lead to the formation of crusts. Chronic lesions are leathery.
Diagnosis can be difficult since this type of dermatitis may look like many other skin lesions.
The main treatment is to remove the offending agent.
What is allergic contact dermatitis?
This is an acute or chronic inflammation, often sharply demarcated in a particular area, caused by skin contact with certain substances.
What causes allergic contact dermatitis?
This type of dermatitis may be caused by a primary chemical irritant or it may be a delayed hypersensitivity reaction (allergic contact dermatitis). This type of reaction occurs when someone is exposed to a substance to which they develop sensitivity. Instead of reacting immediately, the immune system reacts some time later, and signs of this reaction occur only when the person is re-exposed to the allergen. This reaction can take between six and 10 days in the case of strong sensitisers, such as poison ivy, or it may take years with weaker sensitisers. On re-exposure, itching and dermatitis may appear within four to 12 hours.
Certain drugs used on the skin contain ingredients that are a major cause of allergic contact dermatitis. These include antibiotics, antihistamines, anaesthetics and antiseptics.
Plants are another frequent cause contact dermatitis, and there are many potential sensitisers used in the manufacture of shoes and clothing. Metal compounds such as nickel, chromates and mercury, as well as dyes and cosmetics can also cause allergic contact dermatitis.
Irritants may damage normal skin or irritate existing dermatitis. Weak or marginal irritants, such as soap, detergents, acetone or even water, may need several days of exposure to cause signs of damage. Strong irritants, such as acids, alkalis and phenol, cause skin damage within minutes.
Photoallergic or phototoxic contact dermatitis requires exposure to light following the application of certain chemicals to the skin. These appear as an exaggerated response to sunlight. Agents that commonly cause this problem include aftershave lotions, sunscreens and sulphonamide antibiotics in creams or ointments and certain soaps. Medications, taken per mouth, may also cause this form of dermatitis, such as sulphonamide, antibiotics and certain diuretics.
What are the symptoms and signs?
Signs of contact dermatitis range from transient redness to severe swelling, with the formation of large blisters, exudation and crusting. Itching is common.
Any exposed skin that comes into contact with a sensitising or irritating substance may be affected. Typically, dermatitis is initially limited to the site of contact, although it may become widespread.
How is it diagnosed?
Diagnosis can be difficult since this type of dermatitis may simulate many other skin conditions. Typical skin changes and a history of exposure to a particular substance may help, but identifying the specific substance may require careful noting of previous exposure.
Patch testing with a standardised group of contact sensitisers may be useful if careful questioning does not provide the information. A specialist should select the test concentrations, particularly for industrial substances.
Patch testing is often done after the eruption has subsided, as the results may not be conclusive during the acute phase of the condition.
A negative patch test may not rule out contact dermatitis. It may merely mean that the offending agent was not tested.
Skin biopsy may confirm the presence of dermatitis.
How is it treated?
The main treatment is to remove the offending agent. Without this, the dermatitis may promptly recur and any treatment is unlikely to be effective.
During the acute phase, applying thin gauze cloths soaked in saline or tap water to the lesion can be soothing and cooling. In severe and extensive cases, oral corticosteroids can be helpful, particularly when there is facial inflammation.
Cortisone creams and ointments are not useful if there are blisters present, but they can be used once the dermatitis has settled a little.
Antihistamines and allergen desensitisation are not effective in contact dermatitis.
What is the course of allergic contact dermatitis?
The course varies. If the source is removed, the redness disappears within a few days and the blisters dry up. As the inflammation subsides, there may be some scaling or temporary thickening of the skin. Continuing exposure to the causative substance usually perpetuates the dermatitis.
Atopic dermatitis is a chronic, itching, superficial inflammation of the skin.
It is often associated with a personal or family history of related problems such as hay fever and asthma.
The exact cause is not known, but there is strong evidence for a genetic predisposition.
Itching is a constant feature.
Emotional stress, temperature or humidity changes, bacterial skin infections, house dust mite, foodstuffs and wool contact may also aggravate the condition.
What is atopic dermatitis?
This is a chronic, itching, superficial inflammation of the skin, often associated with a personal or family history of related problems such as hay fever and asthma.
What causes atopic dermatitis?
The exact cause is not known (see above).
Prick tests on the skin are commonly positive, but the relevance of these results is controversial.
People who suffer from atopic dermatitis often have high levels of an immune substance called IgE.
What are the symptoms and signs of atopic dermatitis?
The condition may start within the first few months of life with red, weeping, crusting lesions on the face, scalp, and the limbs.
In older children or adults it may be more localised and chronic.
Itching is a constant feature. The constant itch leads to rubbing and scratching, which in turn leads to more itching.
The redness and thickened skin is most commonly found in the creases of the elbows and knees, the eyelids, neck and wrists. The rash may become more widespread across the rest of the body.
Secondary bacterial infections and swollen glands are common.
Because people with atopic dermatitis often use drugs, over-the-counter or prescribed, contact dermatitis frequently complicates this condition. There are many substances that irritate the skin and can exacerbate the condition.
Emotional stress, temperature or humidity changes, bacterial skin infections and wool can also aggravate the condition. (see above)
People with atopic dermatitis generally have dry skin.
How is atopic dermatitis diagnosed?
Diagnosis is entirely clinical – that means the doctor examines the skin condition and asks questions about it to make the diagnosis. It is based on the distribution of the lesions, how long they have been there and whether there is a family history of allergic disorders.
How is atopic dermatitis treated?
There are several general measures:
Avoid topical antibiotics and antiseptics.
Corticosteroid creams or ointments applied to the skin twice a day are the most effective drugs. These should be mixed with, or used as well as, moisturising creams such as white petrolatum or hydrogenated vegetable oils. Prolonged use of high potency corticosteroid creams should be avoided, particularly in infants. Corticosteroids should be used with extreme caution on the face and skin folds. Corticosteroid creams can become ineffective with frequent use. This can be avoided by alternating their use with simple moisturisers for a week or more. The main side effect of topical corticosteroids is thinning (atrophy) of the skin.
Oils help to lubricate the skin and these and corticosteroid creams should be used within minutes of bathing before the skin is dried to help with moisturising.
Children may need a sedative antihistamine at bedtime when the itching is at its worst.
Fingernails should be kept short to minimise damage when scratching.
If the home treatment is not effective, the person may need to be treated in hospital.
Secondary bacterial infections are treated with antibiotics.
Oral corticosteroids are used as a last resort.
Older adults may benefit from psoralen with high intensity ultraviolet light. (Psoralen is a photosensitising drug meaning it makes you more sensitive to sunlight.)
What is the course of atopic dermatitis?
The course is unpredictable. More than 50% of patients will still experience dermatitis when they reach adulthood.
Atopic dermatitis can be complicated by the development of cataracts in patients in their 20s and 30s. Herpes simplex infection can sometimes induce a serious illness with a high temperature, so people with this problem should be especially careful about exposure to herpes simplex.
What is seborrhoeic dermatitis?
This is an inflammatory scaling of the scalp, face and sometimes other areas. In spite of the name of the illness, the composition and flow of the oily substance, sebum, which is secreted by the skin, is usually normal.
What are the symptoms and signs of seborrhoeic dermatitis?
Onset in adults is usually gradual. The dermatitis is usually seen only as a dry or greasy diffuse scaling of the scalp with variable itching.
In severe disease, yellow-red scaling papules appear along the hairline, behind the ears, in the outer ear, on the eyebrows, on the bridge of the nose, in the folds of the nose and over the chest bone (sternum). The upper back and skin folds such as the axillae and groin may also be involved.
Seborrhoeic dermatitis may also occur in children up to the age of two years. The most common presentation is in the form of greasy scales on the scalp (cradle cap). This form of dermatitis may be more widespread and involve the diaper area and the rest of the body.
What is the treatment of seborrhoeic dermatitis?
Treatment depends on the severity and location of the illness.
In adults, zinc, sulphur and salicylic acid preparations or tar shampoo should be used daily or every other day until the dermatitis is controlled. It should then be used twice a week.
A corticosteroid lotion can be rubbed into the scalp or other hairy areas until the redness subsides.
Hydrocortisone cream is best for facial areas.
In infants, a mild baby shampoo is used daily and a hydrocortisone cream rubbed in twice a day. For thicker lesions, 10% salicylic acid in mineral oil, or a corticosteroid gel is applied at bedtime to the affected areas. The scalp is shampooed daily until the thick scale is gone.
Salicyclic acid preparations should not be used for longer than one week.
What is the course of seborrhoeic dermatitis?
The condition runs a chronic course with relapse and remissions. Seborrhoeic dermatitis in adults is incurable. In infants, spontaneous resolution is the rule.
The prognosis is better than in atopic dermatitis. Very rarely, in infants or adults, the condition may become generalised.
What is nummular dermatitis?
Nummular dermatitis is characterized by roundish areas of dermatitis. The size of the lesions is variable.
What causes nummular dermatitis?
The cause is not known. It is seen most often in adults. Exacerbations and remissions may occur.
What are the symptoms and signs of nummular dermatitis?
The round lesions often start as itchy patches of blisters that join together. They later ooze serum and form crusts.
The lesions may be widespread. They may be more prominent on the front of the limbs and on the buttocks. However, they also appear on the trunk.
How is nummular dermatitis treated?
There is no uniformly effective treatment. Moisturising creams and emollients should be applied twice or thrice daily and can be used to dilute cortisone creams and ointments.
Oral antibiotics are indicated when secondary infection is present.
After the lesion has dried, a corticosteroid cream or ointment should be rubbed in three times a day. At bedtime, corticosteroid cream can be applied and then covered with polythene and left on overnight. This is called occlusive treatment.
When there are not too many lesions and they do not respond to the above treatment, corticosteriods injected into the lesions may be helpful.
In more widespread cases, which resist the usual treatment, ultraviolet B radiation alone or ultraviolet A with oral psoralens may help. Occasionally oral corticosteroids are needed.
Chronic dermatitis of the hands and feet
What is chronic dermatitis of the hands and feet?
The hands and feet are frequent sites of inflammation – the hands because they are exposed to mechanical and chemical trauma, and the feet because they are constantly in a warm and moist environment.
The eruption often becomes chronic and can be crippling at home or work.
The following types of eruptions can involve the hands and feet:
Contact dermatitis is common.
Housewives eczema – a hand dermatitis often seen in housewives and other people whose hands are often wet. Washing dishes, clothes and babies undoubtedly makes it worse. Repeated exposure to detergents, water or prolonged sweating under rubber gloves may irritate the skin. Multiple factors are involved in this condition.
Pomphylox is a chronic condition in which there are deep-seated itchy vesicles (blisters) on the palms, the sides of the fingers and soles of the feet. Scaling, redness and oozing then follow the blisters. There is no known cause.
Psoriasis, which is localised to the hands, is seen on the back of the hands as the typical thick, silvery, scaling papules or plaques. Lesions on the palms may be pustular. The pitting of the fingernails that is seen in psoriasis can also occur with other types of dermatitis.
Recalcitrant pustular eruptions of the palms and the soles are display crops of deep-seated pustules that are not associated with any infection. The cause is not known and they are difficult to treat. They may be associated with psoriasis elsewhere.
Fungal infection of the feet is common, but uncommon on the hands. Patients with dermatitis on their hands should be examined for fungal infection of the feet, since this can produce a non-specific dermatitis of the hands - a hypersensitivity reaction.
How is chronic dermatitis of the hands and feet treated?
Treatment should be aimed at removing the cause wherever possible. If no specific cause is found, the following general measures can be used:
Topical moisturising creams and emollients are essential.
Topical corticosteroid three times a day can be applied to relieve itching.
Oral antibiotics should be given if there appears to be secondary bacterial infection.
Wet chores should be limited to short periods and white cotton gloves should be worn under rubber gloves.
A short course of oral prednisone is sometimes needed.
If the dermatitis is long-standing and disabling, then treatment in hospital may be beneficial.
Ultraviolet radiation applied to the hands and feet is often very effective.
Erythroderma (exfoliative dermatitis)
What is erythroderma?
This is a severe, widespread redness and scaling of the skin.
What is the cause of erythroderma?
In 50% of cases, no cause can be found. In some patients it is secondary to certain other types of dermatitis, such as atopic or contact dermatitis. It can also be produced by drugs such as penicillin, sulfonamides, isoniazid, phenytoin or barbiturates. Psoriasis may become erythrodermic. It can also result from something irritating that is applied to the skin. It can also be associated with lymphoma.
What are the symptoms and signs of erythroderma?
The onset may be gradual or rapid.
The entire skin surface becomes red, scaly, thickened and occasionally crusted. Itching may be severe or not present.
There is usually generalised swelling of the lymph glands. The temperature may be raised, or the person may feel cold from excessive heat loss because of increased blood flow to the skin. This can also cause weight loss, low protein in the circulation, iron deficiency and in some unusual cases, a particular type of heart failure.
How is erythroderma diagnosed and treated?
Erythroderma is a serious condition and every attempt must be made to see if there is an underlying cause. A history of signs of another type of dermatitis may be helpful.
It is often necessary to hospitalise the patient. Because drug eruptions and contact dermatitis cannot be ruled out by history alone, all drugs should be stopped if possible. Local treatment is the same as for contact dermatitis.
What is stasis dermatitis?
This is a persistent inflammation of the skin of the lower legs with a tendency to brown pigmentation. It is associated with varicose veins.
What are the symptoms and signs of stasis dermatitis?
The eruption is usually around the ankle. The skin is red with mild scaling and brown discolouration. Swelling (oedema) and varicose veins are often present, but not always. Because of the relative lack of symptoms, the condition is often neglected.
The usual consequences are increasing swelling, secondary bacterial infection and eventual ulceration.
What is the treatment of stasis dermatitis?
The legs must be elevated above the level of the heart to allow adequate blood flow and prevent fluid accumulating in the tissues. Support stockings are essential. Topical moisturising creams and ointments are essential.
Therapy directly to the skin is also used. This varies according to the stage of the process. In the acute stages, tapwater compresses are applied, continuously at first and then intermittently.
If the lesion is infected, a more absorbent dressing is used. When the dermatitis is more acute, a corticosteroid cream should be applied three times a day or incorporated into zinc oxide paste.
Oral antibiotics are essential when cellulitis, bacterial infection of the surrounding tissues, is present.
Localised scratch dermatitis (synonym for lichen simplex chronicus)
What is localised scratch dermatitis?
Localised scratch dermatitis, also called neurodermatitis, is a chronic, superficial, itchy inflammation of the skin. Lesions are well-demarcated, dry, scaly plaques that are thickened and have increased pigmentation in them. They are oval, irregular or angular in shape.
What causes localised scratch dermatitis?
The disease appears to have a strong psychogenic component and allergy seems to play no part. Women are affected more commonly than men, usually between the ages of 20 and 50.
What are the symptoms and signs of localised scratch dermatitis?
In a fully developed plaque the skin is inflamed, with an outer zone of discrete brownish papules and central area of papules covered with scales.
Itching around the anus (pruritis ani) and the vulva (pruritis vulvae) are often instances of localised scratch dermatitis.
The main area affected is the occipital region (the back of the head where it joins the neck), and the arms or legs, particularly the ankles. Vigorous scratching gives transient relief but the itching recurs.
Stress and tension increase the itching and scratching may become a habit.
How is localised scratch dermatitis diagnosed?
Diagnosis is usually made by looking at the skin and excluding other possible causes of dermatitis.
How is localised scratch dermatitis treated?
The person needs to know that the scratching and rubbing produce the skin changes.
Drugs may control the itching. Corticosteroid creams or ointments are the most effective. Moisturising creams or emolients are essential.
What is the outcome of localised scratch dermatitis?
The usual course is chronic. An area of skin starts to itch repeatedly, sometimes with a preceding irritation, often with no apparent reason.
When to see your doctor
Any persistent skin irritation should prompt a visit to the doctor.
(Reviewed by Prof H.F. Jordaan)