The disrupted skin barrier leads to transdermal water loss (leading to the xerosis or dry skin commonly seen in AD) and antigen and allergen penetration of the epidermal layer. Filaggrin mutations are also associated with a decrease in natural antimicrobial peptides found on the skin; subsequently leading to disruption of skin flora and bacterial overgrowth (commonly Staphylococcus aureus overgrowth or colonization).Atopic dermatitis is also associated with the release of pruritogens (molecules that stimulate pruritus or itching) in the skin. Keratinocytes, mast cells, eosinophils and T-cells release pruritogens in the skin; leading to activation of Aδ fibers and Group C nerve fibers in the epidermis and dermis contributing to sensations of pruritus and pain. The pruritogens include the Th2 cytokines IL-4, IL-13, IL-31, histamine, and various neuropeptides. Mechanical stimulation from scratching lesions can also lead to the release of pruritogens contributing to the itch scratch cycle whereby there is increased pruritus or itch after scratching a lesion. Chronic scratching of lesions can cause thickening or lichenification of the skin or prurigo nodularis (generalized nodules that are severely itchy). Diagnosis
AD is typically diagnosed clinically, meaning it is based on signs and symptoms alone, without special testing. Several different criteria developed for research have also been validated to aid in diagnosis. Of these, the UK Diagnostic Criteria, based on the work of Hanifin and Rajka, has been the most widely validated. Treatments
No cure for AD is known, although treatments may reduce the severity and frequency of flares.
Other diseases that must be excluded before making a diagnosis include contact dermatitis, psoriasis, and seborrheic dermatitis.Treatment involves avoiding things that make the condition worse, daily bathing with application of a moisturising cream afterwards, applying steroid creams when flares occur, and medications to help with itchiness. Things that commonly make it worse include wool clothing, soaps, perfumes, chlorine, dust, and cigarette smoke. Phototherapy may be useful in some people. Steroid pills or creams based on calcineurin inhibitors may occasionally be used if other measures are not effective. Antibiotics (either by mouth or topically) may be needed if a bacterial infection develops. Dietary changes are only needed if food allergies are suspected.Atopic dermatitis affects about 20% of people at some point in their lives. It is more common in younger children. Females are slightly more affected than males. Many people outgrow the condition. Atopic dermatitis is sometimes called eczema, a term that also refers to a larger group of skin conditions. Other names include "infantile eczema", "flexural eczema", "prurigo Besnier", "allergic eczema", and "neurodermatitis". Signs and symptoms
People with AD often have dry and scaly skin that spans the entire body, except perhaps the diaper area, and intensely itchy red, splotchy, raised lesions to form in the bends of the arms or legs, face, and neck.AD commonly affects the eyelids, where signs such as Dennie-Morgan infraorbital fold, infra-auricular fissure, and periorbital pigmentation can be seen. Postinflammatory hyperpigmentation on the neck gives the classic "dirty neck" appearance.