Eczema (From Greek ἔκζεμα) is a form of dermatitis or inflammation of the epidermis (the outer layer of the skin). The term eczema is broadly applied to a range of persistent skin conditions. These include dryness and recurring skin rashes that are characterized by one or more of these symptoms: redness, skin edema (swelling), itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding. Areas of temporary skin discoloration may appear and are sometimes due to healed injuries. Scratching open a healing lesion may result in scarring and may enlarge the rash.
In some languages, dermatitis and “eczema” are synonymous, while in other languages “dermatitis” implies an acute condition and “eczema” a chronic one. The two conditions are often classified together.
Classification
Common
• Atopic eczema (aka infantile e., flexural e., atopic dermatitis) is an allergic disease believed to have a hereditary component and often runs in families whose members also have asthma. Itchy rash is particularly noticeable on head and scalp, neck, inside of elbows, behind knees, and buttocks. Experts are urging doctors to be more vigilant in weeding out cases that are, in actuality, irritant contact dermatitis. It is very common in developed countries, and rising.
• Contact dermatitis is of two types: allergic (resulting from a delayed reaction to some allergen, such as poison ivy or nickel), and irritant (resulting from direct reaction to a detergent, such as sodium lauryl sulfate, for example). Some substances act both as allergen and irritant (wet cement, for example). Other substances cause a problem after sunlight exposure, bringing on phototoxic dermatitis. About three quarters of cases of contact eczema are of the irritant type, which is the most common occupational skin disease. Contact eczema is curable, provided the offending substance can be avoided and its traces removed from one’s environment.
• Xerotic eczema (aka asteatotic e., e. craquele or craquelatum, winter itch, pruritus hiemalis) is dry skin that becomes so serious it turns into eczema. It worsens in dry winter weather, and limbs and trunk are most often affected. The itchy, tender skin resembles a dry, cracked, river bed. This disorder is very common among the older population. Ichthyosis is a related disorder.
• Seborrhoeic dermatitis or Seborrheic dermatitis (in infants) is a condition sometimes classified as a form of eczema that is closely related to dandruff. It causes dry or greasy peeling of the scalp, eyebrows, and face, and sometimes trunk. The condition is harmless except in severe cases of cradle cap. In newborns it causes a thick, yellow crusty scalp rash called cradle cap, which seems related to lack of biotin and is often curable.
Less common
• Dyshidrosis (aka dyshidrotic e., pompholyx, vesicular palmoplantar dermatitis, housewife’s eczema) only occurs on palms, soles, and sides of fingers and toes. Tiny opaque bumps called vesicles, thickening, and cracks are accompanied by itching, which gets worse at night. A common type of hand eczema, it worsens in warm weather.
• Discoid eczema (aka nummular e., exudative e., microbial e.) is characterized by round spots of oozing or dry rash, with clear boundaries, often on lower legs. It is usually worse in winter. Cause is unknown, and the condition tends to come and go.
• Venous eczema (aka gravitational e., stasis dermatitis, varicose e.) occurs in people with impaired circulation, varicose veins and edema, and is particularly common in the ankle area of people over 50. There is redness, scaling, darkening of the skin and itching. The disorder predisposes to leg ulcers.
• Dermatitis herpetiformis (aka Duhring’s Disease) causes intensely itchy and typically symmetrical rash on arms, thighs, knees, and back. It is directly related to celiac disease, can often be put into remission with appropriate diet, and tends to get worse at night.
• Neurodermatitis (aka lichen simplex chronicus, localized scratch dermatitis) is an itchy area of thickened, pigmented eczema patch that results from habitual rubbing and scratching. Usually there is only one spot. Often curable through behavior modification and anti-inflammatory medication. Prurigo nodularis is a related disorder showing multiple lumps.
• Autoeczematization (aka id reaction, autosensitization) is an eczematous reaction to an infection with parasites, fungi, bacteria or viruses. It is completely curable with the clearance of the original infection that caused it. The appearance varies depending on the cause. It always occurs some distance away from the original infection.
• There are also eczemas overlaid by viral infections (e. herpeticum, e. vaccinatum), and eczemas resulting from underlying disease (e.g. lymphoma). Eczemas originating from ingestion of medications, foods, and chemicals, have not yet been clearly systematized. Other rare eczematous disorders exist in addition to those listed here.
EPIDEMIOLOGY
The lifetime clinician-recorded prevalence of eczema has been seen to peak in infancy, with female predominance of eczema presentations occurring during the reproductive period of 15–49 years. Although little data on the trend of eczema prevalence over time exists prior to the Second World War (1939–45), the prevalence of eczema has been found to have increased substantially in the latter half of the 20th Century, with eczema in school-aged children being found to increase between the late 1940s and 2000. A review of epidemiological data in the UK has also found an inexorable rise in the prevalence of eczema over time. Further recent increases in the incidence and lifetime prevalence of eczema in England have also been reported, such that an estimated 5,773,700 or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.
SYMPTOMS
Symptoms of eczema can vary greatly in intensity, frequency, and duration among individuals. Symptoms can be minimal and include mild itching and the development of a rash or patch of inflamed skin. Scratching, however, often does not relieve the itch and can lead to increased inflammation, more intense itching, and harder scratching.It can be very difficult to break this cycle of escalating itching, scratching, and inflammation. The scratching cycle can lead to complications from the development of open breaks and lesions in the skin. Complications include a secondary bacterial infection or fungal infection of the surrounding skin and tissues. This is called cellulitis and can be potentially serious, even life-threatening, for some people. Skin areas affected by eczema can also exhibit a variety of characteristics, depending on the individual case. These include flaking, scaling, small red bumps, and/or blistering. Darkening of the area of skin affected by eczema, called hyperpigmentation, may also result. Frequent scratching can also result in thickening of the affected skin. Symptoms frequently begin in infancy and reoccur during childhood. It is not unusual for symptoms to disappear during adulthood, although it can happen, and flare-ups are unpredictable throughout a lifetime. People who are more likely to develop eczema include those with a personal or family history of allergies, allergic rhinitis or asthma
DIAGNOSIS
The list of medical tests mentioned in various sources as used in the diagnosis of Eczema includes:
•Physical exam
•Skin scratch/prick tests – need careful interpretation.
•Blood tests for airborne allergens – often not very useful for diagnosis.
•Eosinophil levels
•IgE levels
•Food diary – to watch for food allergies
PATHOGENESIS
Eczema can be determined by an original chemical irritant or an allergen (ie, a delayed hypersensitivity reaction type IV. The etiology may also include one or more defects in the skin barrier, leading to the dysfunction of the barrier. Multiple factors can alter the physiological protective function, including abnormal lipid metabolism, in particular ceramides, increased protease activity, the defects of the serine protease inhibitors, structural and genetic changes. Although you do not know the specific etiologic and pathogenetic factor of atopic dermatitis, the barrier dysfunction appears to exacerbate the situation by increasing the susceptibility to irritation.
THERAPY
There is no known cure for eczema; therefore, treatments aim to control the symptoms by reducing inflammation and relieving itching.
Treatment