What Are Eczema and Dermatitis?

Eczema is a condition in which inflammation occurs in the relatively shallow layers of the skin; it is also called dermatitis. It is the most common skin condition among patients who visit a dermatology clinic.

Eczema presents a variety of skin symptoms like those below and changes over time.

• Early stage

  Itchy red patches (erythema), small raised bumps (papules), and peeling (scaling) appear on the skin.

• Progressive stage

  Scratching worsens it, and it may ooze fluid (exudate), form blisters (vesicles) or pus-filled spots (pustules), or develop scabs (crusts).

• Chronic stage

  When it persists, the skin thickens and hardens (lichenification) and pigmentation develops.

Early cases are called acute eczema, and prolonged ones are called chronic eczema. When the cause cannot be identified it is simply called “eczema,” but when the cause is known or for certain disease types, the following names are used. Here we explain some representative forms of eczema and dermatitis.

Asteatotic eczema (dry skin eczema)

Asteatotic eczema is a type of eczema caused by dry skin. It occurs when the skin’s barrier function declines due to a reduced sebum film covering the surface, leaving it sensitive to external irritation. It is especially likely in winter and tends to appear on the front of the shins and on the back.

As explained in the “What are eczema and dermatitis?” section, it often becomes rough and flaky, red, and itchy, but even when there is little visible change it is frequently itching due to dryness. As symptoms progress, the skin becomes rough and may develop pigmentation, and it can turn into a condition called nummular (coin-shaped) eczema.

Factors in its onset and worsening are closely tied to lifestyle and environment, such as frequent bathing, use of strong cleansers, dry air, and irritation from clothing. Because sebum production decreases with age, it is common in older people.

The basics of treatment are a washing method that does not strip the sebum, and moisturizing. Applying a moisturizer immediately after bathing in particular lets the oil seal in the skin’s moisture. Depending on symptoms, topical steroids and oral antiallergic medications are also used. If the room’s humidity is too low, using a humidifier is a good idea. Choosing mild soaps and low-friction cotton clothing also helps with prevention. If your symptoms persist or are widespread, please come in for an examination; we will give you skincare guidance and prescribe appropriate medication.

Seborrheic dermatitis

Seborrheic dermatitis is an inflammatory skin condition that tends to develop in areas with heavy sebum production. In adults, the scalp and, on the face, the so-called T-zone (the forehead, between the eyebrows, and around the nose), as well as behind the ears and the armpits, become red, sometimes with white flakes or yellowish crusts. When it appears on the scalp, it is commonly called “dandruff.” When dandruff appears on the head or face, people sometimes mistake it for dry eczema and refrain from washing, which makes it worse. The flakes can also fall onto clothing, drawing unwanted attention.

It also commonly occurs in infancy, where it is one type of infantile eczema. It begins within the first few weeks after birth, with redness on the scalp, forehead, and where the eyebrows grow, and yellow crusts may cling to the hair. It often improves in a short time with proper skincare, but in severe cases medication may be used.

A resident microbe called Malassezia is thought to be involved in the onset of seborrheic dermatitis. The triglycerides in sebum are broken down by this fungus, and the free fatty acids produced as a breakdown product irritate the skin, causing inflammation. Increased sebum secretion due to environment or hormonal balance, and vitamin B deficiency, are also contributing factors.

Treatment is based first on proper washing of the affected area and topical steroids or antifungals. Medication is hard to apply to the scalp, but shampoo-type topical steroids have recently become available. When a vitamin B deficiency seems likely, we may also recommend an oral supplement. Skincare is the most important thing for both prevention and treatment, and we know many parents worry about this, especially with babies. Please feel free to consult us.

Pompholyx / dyshidrotic eczema

Pompholyx is a condition in which small itchy blisters (vesicles) form on the palms and soles. The blisters can break and the skin peel (desquamation), and it is also called dyshidrotic eczema. Because it is a type of eczema, in severe cases scratching can cause raw sores (erosions) and scabs (crusts).

It was once thought to be due to retained sweat, but examining tissue samples has shown that it does not appear to be related to the sweat ducts. Seasonally it is more likely to develop from spring through summer, but quite a few patients develop it in winter as well.

Metal allergy is sometimes involved, and when it is suspected we perform a metal patch test. However, false negatives and false positives can occur, so the results must be interpreted with care. Pompholyx / dyshidrotic eczema can also occur in patients with atopic dermatitis.

Treatment is based on topical steroids or salicylic acid petrolatum and oral antiallergic medication; if a metal allergy is found, removing metal from the mouth in consultation with a dentist may also be considered.

It can be a troublesome condition that is slow to heal or that recurs, but symptoms can sometimes be controlled with appropriate treatment, so please consult us early, before it worsens.

Contact dermatitis(irritant contact dermatitis, allergic contact dermatitis)

Contact dermatitis is an inflammatory skin condition caused by the skin coming into contact with an external substance. Broadly, there are two types: “irritant contact dermatitis” and “allergic contact dermatitis.”

First, irritant contact dermatitis develops when physical or chemical irritation exceeds the skin’s “limit of tolerance” and the cells are damaged. Symptoms such as redness, itching, and swelling appear, confined to the area the irritant touched. Much of what is labeled “eczema or dermatitis of unknown cause” is probably this irritant contact dermatitis. The so-called “diaper dermatitis” of infants and the elderly, in which the diaper itself or urine and stool (especially loose stool) irritate the skin and cause inflammation, is a form of contact dermatitis.

Allergic contact dermatitis, on the other hand, is dermatitis caused by an immune reaction to a substance that has entered the skin. Common causative substances include metals such as nickel, cosmetics, plants (lacquer, ginkgo, etc.), and topical products (creams and medicated patches), and there is a delay of about 24 to 48 hours between contact with the substance and the appearance of symptoms. Once sensitized, a person may show a strong reaction even to a tiny amount of contact.

Treatment is based first on identifying the causative substance and avoiding contact with it. When many everyday products cause irritation, a patch test may be performed. Topical steroids and moisturizers are prescribed according to symptoms, and in severe cases oral medication may be needed.

To avoid contact dermatitis, it is important in daily life to keep the skin clean, avoid excessive washing, and maintain adequate moisturizing.

Atopic dermatitis

Because it is a special disease type, we explain it in detail on a separate page.