Wednesday, 26 October 2016

Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory condition of the skin characterized by intense itching. It usually follows a relapsing course, and is not contagious. It is often referred to as ‘eczema’ which is
a general term for a variety of inflammatory skin conditions. ‘Atopic’ refers to a group of diseases wherein there is an inherited tendency to develop allergic conditions such as hay fever and asthma.

Atopic dermatitis usually begins during infancy and childhood but can occur at any age. Approximately 65% of patients develop symptoms in the 1st year of life, and 85% before the age of 5.
The condition affects 15-20% of school children and 2-10% of adults. There is a tendency of gradual improvement into adulthood but relapses are common.

What Causes Atopic Dermatitis?
The exact cause is unknown but both genetic and environmental factors are involved. A child is more likely to be affected if one or both parents have it or another atopic condition. Various environmental factors trigger or exacerbate symptoms in a predisposed patient at any time.
The condition is also characterized by immune system dysfunction. Atopic dermatitis is an IgE (immunoglobulin E antibody) mediated hypersensitivity reaction, associated with disruption of the normal skin barrier and defects in its cell mediated immunity.

Symptoms and Signs
There are three age related stages which differ in the distribution of the rash. Itching, dry skin and ‘lichenification’ are the commonest features and are seen in all stages.

i. Infancy (under 2 years) The cheeks and chin are affected and appear red with dry patches. Infection is common with oozing and crusting. When the child begins to crawl the back of the arms and front of the legs are affected. Scalp involvement is possible and resembles cradle cap. The nappy area is spared. The child may be restless and irritable due to itch. ii. Childhood (2-12 years)
In this age group the rash appears behind the knees, in front of the elbows, on the sides of the neck, around the mouth, and on the ankles, wrists and hands. The skin around the lips may be inflamed and constant licking causes small painful cracks. The rash is generally papular, with excoriation and lichenification. Light scaly patches on the face are especially common.
In some cases the condition remits for a long time, but relapses may occur around puberty, during periods of stress, and on exposure to irritant cosmetics and skin care products.
iii. Adult stage (puberty and older)
This stage can be similar to childhood in terms of distribution, or it may be localized to specific areas e.g. the hands and feet. Hand dermatitis is common. Affected adults are also more prone toward irritant contact dermatitis.

Patients with atopic dermatitis are susceptible to skin infections, especially staphylococcus aureus, a bacterial infection characterized by redness, oozing and yellow crusts. Viral infection with herpes simplex may occur causing blisters and ulcers; as well as superficial fungal infections which appear as red scaly patches.

Diagnosing Atopic Dermatitis
The diagnosis of atopic dermatitis is a clinical one, based on a personal or family history of atopy together with the typical signs and symptoms. Itching and dry skin are fundamental to the diagnosis.
Investigations are not necessary to make the diagnosis. However certain tests may be done to determine the allergic tendency of the patient and to identify triggers e.g. RAST and skin prick tests.

By Dr Mashudy Ally

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