Contact dermatitis or eczema is a polymorphic inflammation of the skin. It occurs at the site of contact with irritating or antigenic substances. In the acute phase there is occurrence of itching erythema, papules, and vesicles, whereas in the chronic phase there is dryness, hyperkeratosis, and sometimes fissures. Contact dermatitis can be divided into irritant and allergic types. Allergic contact dermatitis is a type-IV T-cell-mediated reaction occurring in a sensitized individual after contact with the antigen/allergen. Such antigens are usually low molecular weight substances (MW approximately 500), called haptens; 3000 contact allergens are known. The diagnosis of contact allergy is made on the basis of the history, clinical findings, and a positive epicutancous test result. Allergic, but not irritative, contact dermatitis can spread beyond the area of contact to other body parts. Eczematous lesions are characterized by a mononuclear infiltrate consisting mainly of T cells in the dermis and epidermis, together with an intercellular epidermal edema that is. spongiosis.
One of the most important steps in treating contact dermatitis is identifying and avoiding the allergens or irritants that affect you. If you can successfully avoid or reduce your exposure to the cause, you shouldn't experience any symptoms. It's not always easy to avoid irritants or allergens that affect you, but your GP or dermatologist (a specialist in treating skin conditions) can find ways to minimise your contact with them. If you are exposed to irritants as part of your job, wear adequate protective clothing to minimise any contact. Tell your employer about your condition, so they can help you avoid the causes as much as possible.
Major research on disease:
Contact dermatitis is an eczematous eruption caused by external agents, which can be broadly divided into irritant substances that have a direct toxic effect on the skin (irritant contact dermatitis, ICD) and allergic chemicals where immune delayed hypersensitivity reactions occur (allergic contact dermatitis, ACD). Contact urticaria is an immediate reaction from exposure to a substance and is mediated by either irritant or immunological mechanisms; it can resemble ICD but the onset is immediate and short lived. Many allergenic chemicals are also irritants and it is thought that ICD enhances the development of ACD.
In Europe about 20% of the general population suffers from contact allergy to at least one contact allergen. Most common are allergies to nickel, fragrances and preservatives. Allergic reactions to chromate and p-phenylenediamine (PPD) are generally less common but occur frequently in occupationally exposed subgroups of the population . Contact dermatitis occurs twice as frequently in women as in men and often starts at a young age, with a prevalence of 15% in 12–16 year olds.