Inflammation of the skin, sometimes due to an allergy but in many cases occurring without a known cause. Many types of dermatitis are better known as eczema (for example, atopic, discoid, infantile, and hand eczema).
Apart from these eczemas, the three main forms of skin inflammation are seborrheic dermatitis, contact dermatitis, and photodermatitis.
Seborrheic dermatitisA common, inflammatory skin condition that causes flaky, white to yellowish scales to form on oily areas such as the scalp or inside the ear. It can occur with or without reddened skin. Cradle cap is the term used when seborrheic dermatitis affects the scalp of infants.
CausesSeborrheic dermatitis is thought to be due to a combination of an over production of skin oil and irritation from a yeast called malessizia. It appears to run in families. Stress, fatigue, weather extremes, oily skin, infrequent shampoos or skin cleaning, use of lotions that contain alcohol, skin disorders (such as acne), or obesity may increase the risk. Neurologic conditions, including Parkinson's disease, head injury, and stroke may be associated with seborrheic dermatitis. Human immunodeficiency virus (HIV) has also been linked to increased cases of seborrheic dermatitis.
SymptomsSeborrheic dermatitis can occur on many different body areas. Typically it forms where the skin is oily or greasy. Commonly affected areas include the scalp, eyebrows, eyelids, creases of the nose, lips, behind the ears, in the external ear, and along skin folds on the middle of the body.
Seborrheic dermatitis in infants, also called cradle cap, is a harmless, temporary condition. It appears as thick, crusty, yellow or brown scales over the child's scalp. Similar scales may also be found on the eyelids, ear, around the nose, and in the groin. Cradle cap may be seen in newborns and small children up to age 3. It is not contagious, nor is it caused by poor hygiene. It is not an allergy, and it is not dangerous. Cradle cap may or may not itch. If it itches, excessive scratching of the area may cause additional inflammation, and breaks in skin may cause mild infections or bleeding.
In general, symptoms of seborrheic dermatitis include:
TreatmentYou can treat flaking and dryness with over-the-counter dandruff or medicated shampoos. Shampoo the hair vigorously and frequently (preferably daily). Loosen scales with the fingers, scrub for at least 5 minutes, and rinse thoroughly. Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, ketoconazole, or selenium.
Shampoos or lotions containing selenium, ketoconazole, or corticosteroids may be prescribed for severe cases. To apply shampoos, part the hair into small sections, apply to a small area at a time, and massage into the skin. If on face or chest, apply medicated lotion twice per day.
Seborrheic dermatitis may improve in the summer, especially after outdoor activities.
For infants with cradle cap:
OutlookSeborrheic dermatitis is a chronic (life-long) condition that can be controlled with treatment. It often has extended inactive periods followed by flare-ups.
Contact dermatitisContact dermatitis is an inflammation of the skin caused by direct contact with an irritating substance.
CausesContact dermatitis is an inflammation of the skin caused by direct contact with an irritating or allergy-causing substance (irritant or allergen). Reactions may vary in the same person over time. A history of any type of allergies increases the risk for this condition.
Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, solvents, or other chemicals. The reaction usually resembles a burn.
Allergic contact dermatitis, the second most common type of contact dermatitis, is caused by exposure to a substance or material to which you have become extra sensitive or allergic. The allergic reaction is often delayed, with the rash appearning 24-48 hours after exposure. The skin inflammation varies from mild irritation and redness to open sores, depending on the type of irritant, the body part affected, and your sensitivity.
Overtreatment dermatitis is a form of contact dermatitis that occurs when treatment for another skin disorder causes irritation.
Common allergens associated with contact dermatitis include:
Some products cause a reaction only when they contact the skin and are exposed to sunlight (photosensitivity). These include shaving lotions, sunscreens, sulfa ointments, some perfumes, coal tar products, and oil from the skin of a lime. A few airborne allergens, such as ragweed or insecticide spray, can cause contact dermatitis.
Exams and testsThe diagnosis is primarily based on the skin appearance and a history of exposure to an irritant or an allergen.
According to the American Academy of Allergy, Asthma, and Immunology, "Patch testing is the gold standard for contact allergen identification." Allergy testing with skin patches may isolate the suspected allergen that is causing the reaction.
Patch testing is used for patients who have chronic, recurring contact dermatitis. It requires three office visits and must be done by a clinician with detailed experience in the procedures and interpretation of results. On the first visit, small patches of potential allergens are applied to the skin. These patches are removed 48 hours later to see if a reaction has occurred. A third visit approximately 2 days later is to evaluate for any delayed reaction. You should bring suspected materials with you, especially if you have already tested those materials on a small area of your skin and noticed a reaction.
Other tests may be used to rule out other possible causes, including skin lesion biopsy or culture of the skin lesion (see skin or mucosal biopsy culture).
TreatmentInitial treatment includes thorough washing with lots of water to remove any trace of the irritant that may remain on the skin. You should avoid further exposure to known irritants or allergens.
In some cases, the best treatment is to do nothing to the area.
Corticosteroid skin creams or ointments may reduce inflammation. Carefully follow the instructions when using these creams, because overuse, even of low-strength over-the-counter products, may cause a troublesome skin condition. In severe cases, systemic corticosteroids may be needed to reduce inflammation. These are usually tapered gradually over about 12 days to prevent recurrence of the rash. In addition to or instead of corticosteroid skin treatment, your doctor may prescribe tacrolimus ointment or pimecrolimus cream.
Wet dressings and soothing anti-itch (antipruritic) or drying lotions may be recommended to reduce other symptoms.
OutlookContact dermatitis usually clears up without complications within 2 or 3 weeks, but may return if the substance or material that caused it cannot be identified or avoided. A change of occupation or occupational habits may be necessary if the disorder is caused by occupational exposure.
PhotodermatitisThis type of dermatitis occurs in people whose skin is abnormally sensitive to light. In the most common form of dermatitis, a cluster of spots or blisters develops on any part of the body exposed to the sun.
Related category• HEALTH AND DISEASE
Source: National Library of Medicine
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