Contact Dermatitis

Contact dermatitis is an inflammatory response of the skin to an antigen or irritant. This includes both allergic and irritant (toxic) types of contact dermatitis, occupational (industrial) dermatitis and consumers' dermatitis from such products as cosmetics and toiletries. Contact dermatitis is unlike Contact Urticaria , in which a rash that appears within minutes of exposure will fade away within minutes to hours. Allergic contact dermatitis is also distinct from irritant contact dermatitis , in which a similar skin condition is caused by excessive contact with irritants. Usually, these symptoms will occur only in the areas that actually came into contact with the irritant or allergen. . Within the dermal layer, various cells congregate around the dilated capillaries to aid in inflammatory response. Papers concerned with the immunology of allergic contact dermatitis are invited for the purpose of bringing to the notice of the clinician, knowledge of important recent advances in the understanding of its theoretical basis, as well as papers on the physiology and pathology of the layer and epidermis in relation to its disturbance in the genesis of irritant dermatitis. Allergy is the term given to a reaction by a small number of people to a substance (known as the allergen) which is harmless to those who are not allergic to it. Substances that cause contact dermatitis in many people include "poisonous" plants such as poison ivy , certain foods, some metals, cleaning solutions, detergents, cosmetics, perfumes, industrial chemicals, and latex rubber.

Contact dermatitis is a skin reaction that occurs after you have been exposed to a substance that either irritates your skin or triggers an allergic response. The main pathologic feature of contact dermatitis is intercellular edema of the epidermis, which may result in intraepidermal vesicle and bullae formation in acute cases and papules, scaling, and lichenification in chronic cases. Irritant contact dermatitis may affect anyone, providing they have had enough exposure to the irritant, but those with atopic dermatitis are particularly sensitive. Almost all workers in wet-work industries, such as hairdressing, cleaning, metal engineering, building-site work and horticulture develop some degree of irritant contact dermatitisChronic contact dermatitis can develop where the removal of the offending agent no longer provides expected relief. And if a friend wears something that you are sensitive to and the two of you are in close contact, you may also develop a skin reaction.

Allergic contact dermatitis occurs most frequently in middle-aged and elderly persons, although it may appear at any age. In contrast to the classical atopic diseases, contact dermatitis is as common in the population at large as in the atopic population, and a history of personal or family atopy is not a risk factor.

The interval between exposure to the responsible agent and the occurrence of clinical manifestations in a sensitized subject is usually 12 to 96 hours, although it may be as early as 4 hours and as late as 1 week. The incubation or sensitization period between initial exposure and the development of skin sensitivity may be as short as 2 to 3 days in the case of a strong sensitizer such as poison ivy, or several years for a weak sensitizer such as chromate. The patient usually will note the development of erythema, followed by papules, and then vesicles. Pruritus follows the appearance of the dermatitis and is uniformly present in allergic contact dermatitis.

Causes of Contact Dermatitis

The common causes of Contact Dermatitis :

• Contributing factors include genetics, concentration, duration of exposure, and presence of other skin diseases.
• Medications (particularly sulfa drugs, thiazides, tetracycline) have been implicated.
• When they come in contact with the allergen, the antibodies promote release of chemicals and hormones called "mediators." Histamine is an example of a mediator.
• The antibody, called immunoglobulin E or IgE, is stored on special cells called mast cells.
• It is the effects of the mediators that cause the symptoms of the allergic reaction, in this case an itchy rash.
• typically develops in areas where something, such as a tight garment, rubs or scratches your skin.
• Stasis dermatitis can occur when fluid accumulates in the tissues just beneath your skin, and typically involves the lower leg.
• The fragrances in soaps, shampoos, lotions, perfumes, and cosmetics can cause a reaction.

Symptoms of Contact Dermatitis

Some common symptoms of Contact Dermatitis :

• Neurodermatitis
• Seborrheic dermatitis
• Warmth of the exposed area (may occur)
• Skin redness or inflammation in the exposed area
• When contact dermatitis is caused by an allergic reaction, it usually causes skin redness, blistering and severe itching.
• In mild cases, there may be only mild redness of the skin.
• Mental changes can include irritability, a slight decrease in attention span, worsened memory, and slower thinking.
• Localized swelling of the skin
• Tenderness of the skin in the exposed area

Treatment of Contact Dermatitis

The inflammation and pruritus of allergic contact dermatitis necessitate symptomatic therapy. For limited, localized allergic contact dermatitis, cool tap water compresses and a topical corticosteroid are the preferred modalities. It is safest to use hydrocortisone on the face. Some treatment methods are :

• Lukewarm water baths (antipruritic)
• Emollients (eg, white petrolatum, Eucerin) may benefit chronic cases.
• Find out precisely what you are allergic to by having comprehensive patch tests
• Azathioprine , ciclosporin or other immunosuppressive agent.
• compresses provide relief. Sedatives and tranquilizers also may help you stop scratching, but your doctor will want to monitor your use of these substances because they can be addictive.
• Common antihistamines include diphenhydramine (Benadryl), hydroxyzine (Atarax), cetirizine (Zyrtec), loratadine (Claritin) and fexofenadine (Allegra). Of these, the last three are less likely to cause drowsiness.
• Localized swelling of the skin
• Treatment consists of correcting the condition that causes fluid to accumulate in your legs or ankles for extended periods.
• Initial treatment includes thorough washing with lots of water to remove any trace of the irritant that may remain on the skin.
• Your doctor probably will suggest a nonirritating ointment or cream that contains few potential allergens.

When the dermatitis is particularly acute or widespread, systemic corticosteroids should be used. In instances when further exposure can be avoided, such as poison ivy dermatitis, there should be no hesitation in administering systemic corticosteroids. This is a classic example of a self-limited disease that will respond to a course of oral corticosteroid therapy. The popular use of a 4- to 5-day decreasing steroid regimen often results in a flare-up of the dermatitis several days after discontinuing the steroids. It is probably best to continue the treatment for 10 to 14 days. There seems to be no need for prolonged antihistamine therapy in such instances. The response to systemic corticosteroids is generally dramatic, with improvement apparent in only a few hours. Three rules that might be applied to systemic corticosteroid therapy in acute contact dermatitis are (a) use an inexpensive preparation such as prednisone; (b) use enough (1 mg/kg); and (c) avoid prolonged administration (rarely more than 2 weeks of therapy is required).

Diagnosis of Contact Dermatitis

The skin conditions most frequently confused with allergic contact dermatitis are seborrheic dermatitis, atopic dermatitis, psoriasis, and primary irritant dermatitis. In seborrheic dermatitis, there is a general tendency toward oiliness of the skin, and a predilection of the lesions for the scalp, the T-zone of the face, midchest, and inguinal folds.

Atopic dermatitis often has its onset in infancy or early childhood. The skin is dry, although pruritus is a prominent feature, it appears before the lesions and not after them, as in the case of allergic contact dermatitis. The areas most frequently involved are the flexural surfaces. The margins of the dermatitis are indefinite, and the progression from erythema to papules to vesicles is not seen.

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