Atopic eczema commonly occurs in patients with a past medical or family history of atopic disease such as asthma and hay fever. The majority of those likely to present with atopy will do so in the first year of life. In half of patients, the disorder will remit by the age of 15 years.
The pathophysiology of atopic eczema is not fully understood. Underlying genetic factors such as variants in the filaggrin gene contribute to a state in which inflammation is caused by high levels of circulating IgE antibodies, coupled with abnormal Tcell
activation in reaction to com monly encountered allergens, such as house-dust mites, and exacerbating factors such as chemicals and stress. The resulting inflammation is pruritic, and affects both the dermis and the epidermis
Clinical Signs
Atopic eczema can present in a variety of different ways, but most commonly with general skin dryness or itching (pruritus) with itchy, red, scaly patches on
the flexor creases of the body. In the first 6 months of life it can present as a symmetrical erythematous eruption affecting the face, trunk and limbs. As the child reaches 2 years, the eruption increasingly affects the flexures. Acute eczematous lesions are vesicular and can weep. Dry skin, excoriations and lichenification (thickening of
the skin, with accentuated crease marks) all occur, and these are aggravated by the child scratching or rubbing the affected skin (the itch–scratch cycle). The pruritus often causes difficulty with sleep. The skin often feels rough to the touch owing to the
dryness of eczema, and in eczema patients fish-like scaling of the skin can sometimes occur without inflammation (ichthyosis vulgaris). Atopic eczema can also involve the nail beds, causing ridging or pitting. Diagnosis is usually clinical, although allergen
sensitivity tests, such as skin prick testing or RAST (radioallergosorbent assay) tests, can sometimes be helpful. Blood eosinophilia is often seen.
Complications
Eczematous areas are prone to secondary infection.
Bacterial colonization is common with Staphylococcus aureus and occasionally streptococci. Viral infections can occur, e.g. Herpes simplex, which in atopic patients can develop into the severe condition eczema herpeticum.
Management
Conservative management Educating the patients and their family is very important in the management of atopic eczema. Various lifestyle changes can lessen skin irritation: loose-fitting cotton clothing, avoiding heat and known irritants (e.g. wool, and occupational irritants or allergens), filing the nails to limit scratching. If pet hair is thought to aggravate the disease care should be taken to minimize contact.
Efforts to reduce the presence of house-dust mites can sometimes be helpful. Dietary changes are rarely helpful unless there is a history of reaction to specific foods.
Both local and national support groups exist for patients with atopic eczema; details of both should be made available to the patient. In children, it should be made clear to the patient that the condition improves in the majority of cases and often remits by the teenage years. Topical therapy Topical therapy controls atopic eczema in most patients, usually with a combination of emollients (moisturizers), alternatives to soap (e.g.
aqueous cream) and topical steroids. Emollients Aqueous cream, emulsifying ointment
and bath-oil emollients moisturize the skin, hydrating the surface layers and reducing pruritus.
Topical steroids
Topical steroids of different
potencies are used, depending on the body site being
treated. The mildest is 1% hydrocortisone, which
is usually sufficient for the face and flexures, where
the skin can easily become atrophic with the use of
stronger steroids. For other body sites, potent steroids
such as betamethasone (Betnovate) preparations are
often needed.
Medicated bandages Bandages may be useful in
excoriated or lichenified eczema, improving the
absorption of topical medication and providing a
barrier against scratching. With exudative eczema,
non-medicated wet wraps may help.
Antibiotics and antiseptics These are used to treat the
infective complications of eczema (usually bacterial,
with Staphylococcus aureus).
Systemic therapy Antihistamines Sedative antihistamines,
e.g. hydro xyzine, given at night may help
reduce scratching in severe cases.
Oral antibiotics and antiviral agents Flucloxacillin
given four times daily (qds) is used to treat
secondary staphylococcal infection, and penicillin
V qds for streptococcal infections. Aciclovir is used
to manage eczema herpeticum and in severe cases
may need to be given intravenously as inpatient
therapy.
Second-line treatments Severe eczema unresponsive
to treatment can be treated by a course of PUVA or a 12-week course of ciclosporin or azathioprine.
However, these are associated with significant side
effects and require careful monitoring.