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CLINICAL FEATURES OF ATOPIC DERMATITS (ECZEMA)

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.