Dermatitis

Dermatitis, also known as eczema, is a group of diseases that results in inflammation of the skin. These diseases are characterized by itchiness, red skin and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to the entire body.

Dermatitis is a group of skin conditions that includes atopic dermatitis, allergic contact dermatitis, irritant contact dermatitis and stasis dermatitis.The exact cause of dermatitis is often unclear. Cases may involve a combination of irritation, allergy and poor venous return.The type of dermatitis is generally determined by the person's history and the location of the rash.For example, irritant dermatitis often occurs on the hands of people who frequently get them wet.Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin.

Treatment of atopic dermatitis is typically with moisturizers and steroid creams. The steroid creams should generally be of mid- to high strength and used for less than two weeks at a time as side effects can occur. Antibiotics may be required if there are signs of skin infection.Contact dermatitis is typically treated by avoiding the allergen or irritant. Antihistamines may help with sleep and to decrease nighttime scratching.

Dermatitis was estimated to affect 245 million people globally in 2015.Atopic dermatitis is the most common type and generally starts in childhood.In the United States, it affects about 10–30% of people. Contact dermatitis is twice as common in females than males.Allergic contact dermatitis affects about 7% of people at some point in time.Irritant contact dermatitis is common, especially among people who do certain jobs; exact rates are unclear.

Signs and symptoms

Dermatitis of the hand

Dermatitis symptoms vary with all different forms of the condition. They range from skin rashes to bumpy rashes or including blisters. Although every type of dermatitis has different symptoms, there are certain signs that are common for all of them, including redness of the skin, swelling, itching and skin lesions with sometimes oozing and scarring. Also, the area of the skin on which the symptoms appear tends to be different with every type of dermatitis, whether on the neck, wrist, forearm, thigh or ankle. Although the location may vary, the primary symptom of this condition is itchy skin. More rarely, it may appear on the genital area, such as the vulva or scrotum.Symptoms of this type of dermatitis may be very intense and may come and go. Irritant contact dermatitis is usually more painful than itchy.

Although the symptoms of atopic dermatitis vary from person to person, the most common symptoms are dry, itchy, red skin. Typical affected skin areas include the folds of the arms, the back of the knees, wrists, face and hands. Perioral dermatitis refers to a red bumpy rash around the mouth.

Dermatitis herpetiformis symptoms include itching, stinging and a burning

sensation. Papules and vesicles are commonly present.The small red bumps experienced in this type of dermatitis are usually about 1 cm in size, red in color and may be found symmetrically grouped or distributed on the upper or lower back, buttocks, elbows, knees, neck, shoulders, and scalp. Less frequently, the rash may appear inside the mouth or near the hairline.

The symptoms of seborrheic dermatitis, on the other hand, tend to appear gradually, from dry or greasy scaling of the scalp (dandruff) to scaling of facial areas, sometimes with itching, but without hair loss.In newborns, the condition causes a thick and yellowish scalp rash, often accompanied by a diaper rash. In severe cases, symptoms may appear along the hairline, behind the ears, on the eyebrows, on the bridge of the nose, around the nose, on the chest, and on the upper back.

Cause

The cause of dermatitis is unknown but is presumed to be a combination of genetic and environmental factors

Environmental

The hygiene hypothesis postulates that the cause of asthma, eczema, and other allergic diseases is an unusually clean environment. It is supported by epidemiologic studies for asthma.[The hypothesis states that exposure to bacteria and other immune system modulators is important during development, and missing out on this exposure increases risk for asthma and allergy. While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites,with up to 5% of people showing antibodies to the mites, the overall role this plays awaits further corroboration.

Genetic

A number of genes have been associated with eczema, one of which is filaggrin. Genome-wide studies found three new genetic variants associated with eczema: OVOL1, ACTL9 and IL4-KIF3A. Eczema occurs about three times more frequently in individuals with celiac disease and about two times more frequently in relatives of those with celiac disease, potentially indicating a genetic link between the conditions.

Diagnosis

Diagnosis of eczema is based mostly on the history and physical examination.In uncertain cases, skin biopsy may be useful. Those with eczema may be especially prone to misdiagnosis of food allergies.

Patch tests are used in the diagnosis of allergic contact dermatitis.

Classification

The term "eczema" refers to a set of clinical characteristics. Classification of the underlying diseases has been haphazard with numerous different classification systems, and many synonyms being used to describe the same condition.

A type of dermatitis may be described by location (e.g., hand eczema), by specific appearance (eczema craquele or discoid) or by possible cause (varicose eczema). Further adding to the confusion, many sources use the term eczema interchangeably for the most common type: atopic dermatitis.

The European Academy of Allergology and Clinical Immunology (EAACI) published a position paper in 2001, which simplifies the nomenclature of allergy-related diseases, including atopic and allergic contact eczemas.[31] Non-allergic eczemas are not affected by this proposal.

Terminology

There are several types of dermatitis including atopic dermatitis, contact dermatitis, stasis dermatitis and seborrheic eczema. Many use the term dermatitis and eczema synonymously.

Others use the term eczema to specifically mean atopic dermatitis.Atopic dermatitis is also known as atopic eczema. In some languages, dermatitis and eczema mean the same thing, while in other languages dermatitis implies an acute condition and eczema a chronic one.