Atopic dermatitis (AD) or eczema is a common skin disease that has seen
a rapid rise with industrialization. In fact, it is the fourth most
costly skin disease in the US. The amount of money spent on treating
eczema is $2.6 billion annually.
This disease is marked by an ‘itch that rashes’, occurs at
any age and has a great psychological and sociological impact. The lifetime
prevalence of atopic dermatitis is estimated to be between 10% to 20%
in children and 1% to 3% in adults. However, 70-95% of cases occur before
5 years of age. Moreover, it is more common among girls than boys. The
pathogenesis of the disease is still under research. Its primary causes
are associated with heredity of genes, environmental interactions, skin
barrier disorders, and immunological reactions.
Diagnostic and indicative features
The diagnosis of atopic dermatitis involves taking a medical history
and physical screening of the patient. There are no laboratory tests used
to diagnose eczema, instead the clinical features of the disease play
a major role in its comprehensive prognosis.
In 1980, Doctors Hanifin and Rajka established a chart of diagnostic
features, which was developed upon by further research from other doctors.
The American Academy of Dermatology Consensus Conference on Pediatric
Atopic Dermatitis (International Symposium on AD, Oregon, US) also declared
its own diagnostic approach.
Based on these approaches, the first step to the diagnosis of eczema
is the ruling out of other skin diseases like contact dermatitis, seborrheic
dermatitis, cutaneous lymphoma, etc. Thereafter, the diagnosis is based
on primary and associated features of eczema.
As a rule, the prognosis must be based on the three standard stages of
the disease - infantile, childhood and adult – often with latent
phases in between. At each age period the condition may be diagnosed as
acute (extensive eczema present), subacute (only a limited amount of eczema
patches), and/or chronic. Furthermore, the disease must be categorized
as either intrinsic or extrinsic. Intrinsic atopic dermatitis is the non-allergic
kind, with xerosis (dry skin) and occurrence at a young age as its other
basic indicators. Extrinsic atopic dermatitis is generally associated
with a medical history (either personal or hereditary) of respiratory
allergy.
Eighty per cent of patients with eczema generally go on to develop allergic
rhinitis or asthma later in childhood, while there is a simultaneous improvement
in the eczema. However, the atopic dermatitis actually becomes latent
and often recurs later in life in up to 40% of cases.
Primary features common to all stages of atopic dermatitis are:
- Severe skin lacerations which are extremely pruritic (itchy) erythematous
papules (red bumps) and thin plaques (crusty skin patches) with secondary
skin peeling
- Vesicles and serous scabs in red and blotchy skin
locations
- Subacute skin lesions seen in the form of blotchy papules
and plaques, followed by scaling and peeling of the skin
- Chronic
atopic dermatitis is marked by dense, thickened plaques of skin with
lichenification (marked skin blotches) combined with
prurigo nodularis
or 'picker's' nodules due to all the scratching.
- Recurrent
skin damage may cause post-inflammatory hyper (too much), hypo (not
enough) or depigmentation (loss) of the
skin color.
- Pruritus (itchiness): Severe pruritus or itchiness is
the fundamental aspect of atopic dermatitis. The itchiness
aggravates in the evening
and by sweat or contact with woolen clothing. The itchiness
generally results
in rubbing and scratching which further aggravates the
condition, which may result in skin reddening, hemorrhagic crusts,
lichenified
plaques
and prurigo nodularis.
- Xerosis: 78-98% atopic dermatitis
cases are also marked by constant, widespread, dry flaking skin without
swelling.
It
is a skin barrier
disorder caused by less water content in the stratum
corneum - the outer layer
of skin - and it facilitates the entry of allergens
and hence worsens the already itchy condition.
- Papular
eczema marked by small perifollicular papules are generally reported
in people of Asian and African
descent
but rarely in
Caucasian people.
Associated clinical features common to all stages of atopic dermatitis
are:
Keratosis pilaris: This is a cosmetic condition caused by extreme keratinization
that results in horny plugs within hair follicle cavities, mainly in the
upper arms and thighs in adults and on the cheeks in children.
Ichthyosis vulgaris: Fifty per cent of atopic dermatitis cases develop
this disorder marked by extreme scaling of the skin.
Palmoplantar hyperlinearity: These are highly marked palmar (hands) and
plantar (feet) skin folds that occur more in atopic dermatitis patients
with ichthyosis vulgaris.
Lichen simplex chronicus: Constant rubbing and scratching thickens the
skin and bloats it in places causing this problem.
Prurigo nodularis: Numerous extremely itchy skin nodules develop mainly
on the extremities (especially the front of the thighs and legs).
Infantile features
In 75-90% of patients, atopic dermatitis develops before the age of 5
and usually not before the age of 2 months. It is marked by acute skin
inflammation.
In infants who are not yet crawling, eczema lesions occur more in body
parts that come in contact with allergens in bedding, like the face, scalp
and supple areas of the extremities. Once the infant starts crawling,
it occurs more in areas like the knees. Associated features include:
Dennie-Morgan lines: These are proportioned and marked single or double
skin folds that develop below the edge of the lower eyelid in some infants
at or right after birth. It is accompanied with periorbital edema, lichenification
and darkening under the eyes ('allergic shiners').
Childhood features
In the span of 2 to 12 years of age, the clinical features become more
adult like. Hence, lesions become milder and locations change to the antecubital
(inner elbow) and popliteal (back of the knee) fossae, posterior neck,
hands etc. Associated features are:
Pityriasis alba: Infants and children may suffer from hypopigmentation
mostly on the face. It is more prominent in kids with darker skin color.
Cheilitis: Here the lips become dry, brittle, chapped and develop fissures.
Adult features
In adults, atopic dermatitis occurs as chronic inflammation with lichenification
and scale, which increases with age. It occurs in the following body parts:
- Areas that have flexural features (creases, curves and bends)
- On
the head and neck region accompanied with severe periocular and eyelid
conditions
- Extremities, with acute cases developing generalized
exfoliative erythroderma
- The hand is a very common spot for eczema
Clinical response of atopic dermatitis to various therapies
Prevention is always better than cure so the conventional procedure in
the management of atopic dermatitis is reducing the symptoms by identifying
the triggers (allergens) and avoiding them.
The standard therapeutic approach is aimed at restoring the skin barrier
functions with use of skin hydration creams and emollients (that combine
moisturizers and topical corticosteroids). In atopic dermatitis, the skin
barrier disorder occurs due to an abnormality in skin lipids, which in
turn results in greater transepidermal water loss. This is caused by genetic
alterations of the epidermal barrier protein filaggrin.
Other therapeutic options are wet dressings, antibiotics for infections,
and antihistamines. In acute cases where other treatments fail, systemic
therapies are often implemented. Stress management and patient counseling
is also a vital part of therapy.
Clinical disadvantages
Atopic dermatitis also has quite a few complications like infection,
edema and erythroderma. There are also treatment related complications
like aggravated secondary infection, cutaneous atrophy, ocular cataracts,
steroid rosacea and perioral dermatitis, osteoporosis, altered body habitus,
Addisonian-like symptoms, etc. In children, it may cause growth retardation.
There are also many syndromes associated with the intolerance of drugs
and topical preparations used to treat the eczema.
