Eczema also known as atopic dermatitis is an immune-mediated inflammation of the skin. It appears to be triggered by genetic and environmental factors. The main symptoms are itching, redness and skin thickening.
AD primarily affects children in urban areas or developed countries,and prevalence has increased over the last 30 yr; 15 to 30% of children and 2 to 10% of adults are affected worldwide. The unproven hygiene hypothesis is that decreased early childhood exposure to infectious agents (ie, because of more rigorous hygiene regimens at home) may increase the development of allergic reactions to environmental allergens and autoimmunity to self-proteins. Many patients or family members who have AD also have asthma or allergic rhinitis.
Signs and symptoms:
AD usually appears in infancy, typically by 3 mo. In the acute phase, lasting 1 to 2 mo, red, weeping, crusted lesions appear on the face and spread to the neck, scalp, extremities, and abdomen. In the chronic phase, scratching and rubbing create skin lesions (typically erythematous macules and papules that lichenify with continued scratching). Lesions typically appear in the antecubital and popliteal fossae and on the eyelids, neck, and wrists and may occasionally become generalized. Lesions slowly resolve to dry scaly macules that can fissure and facilitate exposure to irritants and allergens. In older children and adults, intense pruritus is the key feature. Patients have a reduced threshold for perceiving itch, and itch worsens with allergen exposures, dry air, sweating, local irritation, wool garments, and emotional stress.