Knowra Allergic contact dermatitis Allergic contact dermatitis Allergic contact dermatitis is an itchy skin inflammation caused by a delayed immune reaction to a substance contacting the skin. It typically appears where exposure occurred, though it can spread beyond that area.
Type IV hypersensitivity : An immune reaction mediated by sensitized T cells, typically developing hours to days after exposure. This delayed immune-response class accounts for the rash after skin contact.
Patch test : A diagnostic test that applies suspected allergens to the skin under controlled conditions and checks for delayed reactions. It can identify the substance responsible for allergic contact dermatitis.
Irritant contact dermatitis : Skin inflammation caused by direct damage from an irritant, without requiring an allergen-specific immune response. It can look similar but results from irritation rather than allergy.
Allergen avoidance : The prevention strategy of identifying and avoiding substances that provoke an allergic reaction. Avoiding the identified contact allergen helps prevent recurrent dermatitis.
Hapten : A small molecule that can trigger an adaptive immune response after binding to a larger carrier, such as a skin protein. Contact allergens often become immunogenic after binding to proteins in the skin.
Nickel allergy : An immune allergy to nickel that commonly causes contact dermatitis after skin exposure. Nickel in jewelry and other objects is a frequent cause of this condition.
Atopic dermatitis : A chronic, relapsing inflammatory skin disease associated with skin-barrier dysfunction and immune dysregulation. It can resemble contact dermatitis, but its pattern and underlying causes differ.
Hand eczema : Inflammation of the hands that can cause itching, redness, scaling, fissures, or blisters. Repeated occupational or household exposure can make allergic dermatitis a persistent hand problem.
Langerhans cell : A dendritic immune cell in the epidermis that captures antigens and can present them to T cells. These epidermal cells help initiate sensitization to contact allergens.
Poison ivy dermatitis : Allergic contact dermatitis caused by urushiol, an oil found in poison ivy and related plants. It is a recognizable plant-triggered instance of the same delayed reaction.
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