Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness 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 covering the entire body. Dermatitis is also called eczema, but "eczema"

Medical condition

Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash.[1] In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened.[1] The area of skin involved can vary from small to covering the entire body.[1][2] Dermatitis is also called eczema, but "eczema" is often used for the most common type of skin inflammation, atopic dermatitis.[7]

The exact cause of the condition is often unclear.[2] Cases may involve a combination of allergy and poor venous return.[1] The type of dermatitis is generally determined by the person's history and the location of the rash.[1] For example, irritant dermatitis often occurs on the hands of those who frequently get them wet.[1] Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin.[1]

Prevention of atopic dermatitis is typically with essential fatty acids,[4] and may be treated with moisturizers and steroid creams.[5] 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.[8] Antibiotics may be required if there are signs of skin infection.[2] Contact dermatitis is typically treated by avoiding the allergen or irritant.[9][10] Antihistamines may help with sleep and decrease nighttime scratching.[2]

Dermatitis was estimated to affect 245 million people globally in 2015,[6] or 3.34% of the world population. Atopic dermatitis is the most common type and generally starts in childhood.[1][2] In the United States, it affects about 10–30% of people.[2] Contact dermatitis is twice as common in females as in males.[11] Allergic contact dermatitis affects about 7% of people at some point in their lives.[12] Irritant contact dermatitis is common, especially among people with certain occupations, exact rates are unclear.[13]

Terminology

The terms dermatitis and eczema are sometimes used synonymously.[1][14] However the term eczema is often used to specifically mean atopic dermatitis (also known as atopic eczema).[15][7] Terminology might also differ according to countries. In some languages, dermatitis and eczema mean the same thing, while in other languages, dermatitis implies an acute condition and eczema a chronic one.[16]

Signs and symptoms

There are several types of dermatitis, including atopic dermatitis, contact dermatitis, stasis dermatitis, and seborrhoeic dermatitis.[2] Dermatitis symptoms vary with all different forms of the condition. 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.[17][18] 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 on light skin. However, this redness does not appear on darker skin, and dermatitis can appear darker brown or purple in color.[19] 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.[20]

Dermatitis herpetiformis symptoms include itching, stinging, and a burning sensation. Papules and vesicles are commonly present.[21] 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.

The symptoms of seborrhoeic 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.[22] 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.[23]

Complications

People with eczema should not receive the smallpox vaccination due to risk of developing eczema vaccinatum, a potentially severe and sometimes fatal complication.[24] Other major health risks for people with dermatitis are viral and bacterial infections because atopic dermatitis patients have deficiencies in their proteins and lipids that have barrier functions along with defects in dendritic cells and as a result are unable to keep foreign invaders out, leading to recurring infections.[25] If left untreated, these infections may be life-threatening, so skin barrier improvement (such as daily moisturizing to minimize transepidermal water loss) and anti-inflammatory therapy are recommended as preventative measures.[25]

Cause

The cause of dermatitis is unknown, but it is presumed to be a combination of genetic and environmental factors.[2] Eczema is not contagious.

Environmental

The hygiene hypothesis postulates that the cause of asthma, eczema, and other allergic diseases is an unusually clean environment in childhood, which leads to an insufficient human microbiota. It is supported by epidemiologic studies for asthma.[26] The hypothesis states that exposure to bacteria and other immune system modulators is important during development, and missing out on this exposure increases the risk for asthma and allergy.[27] One systematic review of literature on eczema found that urban areas have an increased prevalence of eczema compared to rural areas.[28] While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites,[29] with up to 5% of people showing antibodies to the mites,[30] the overall role this plays awaits further corroboration.[31]

Malnutrition

Essential fatty acid deficiency results in a dermatitis similar to that seen in zinc or biotin deficiency.[4]