Clinical manifestations of atopic dermatitis

By Cristiano Antonino On Nov 7, 2022

Atopic dermatitis is one of the most frequent skin diseases because it manifests itself in both children and adults with percentages of up to 20% and 3% of cases respectively

The term dermatitis, which is non-specific and generic, only indicates that the disease is characterised by inflammation of the epidermis and dermis, and is therefore not infectious.

Not all dermatitis can be diagnosed as atopic dermatitis or atopic eczema

Furthermore, in atopic dermatitis the skin manifestations are typical and vary according to the age of the person and are decisive in making the clinical diagnosis.

But first of all, atopy must be present.

What is atopy?

Atopy is a biological condition and it is the intrinsic characteristic of the disease that differentiates it from all other forms of dermatitis such as allergic contact dermatitis or dermatitis of an irritative nature.

Therefore, only if this condition is present can a certain skin inflammation be diagnosed as atopic dermatitis.

The term atopy refers to a personal or familial hypersensitivity of the skin and/or mucous membranes to common environmental stimuli that results in increased IgE production and the development of symptoms such as conjunctivitis or asthma, or skin manifestations such as eczema.

Three important elements emerge from the above definition:

Familiarity: this refers to the presence of atopic diseases in relatives of the person with atopic dermatitis because a genetic predisposition is present. Studies have shown alterations in chromosomes 3, 5 and 11 and the presence of atopic dermatitis in 80% of homozygotic twins, as identical twins share the same DNA, and only in 30% of heterozygotic twins. Furthermore, a defect in a specific protein of the epidermis, filaggrin, has recently been demonstrated, an alteration also present in ichthyosis vulgaris.
Hypersensitivity of the skin or mucous membranes: various substances, chemical, physical, biological, are capable of triggering a series of diseases, called atopic, such as bronchial asthma, rhinitis or conjunctivitis. Therefore, within a specific household, one person may be affected by bronchial asthma while another by atopic dermatitis. Apparently different diseases whose common denominator is atopy, which is expressed clinically in different ways in different individuals.
IgE hyperproduction: increased IgE antibodies in the serum as a biological defence response to various possible triggering and irritating factors or as a consequence of an allergy that the person with atopic dermatitis may have developed. I emphasise that atopic dermatitis is not an allergy but could develop it as reported below.

Clinical manifestations of atopic dermatitis

A person is born with atopic dermatitis, a constitutive defect in the outermost layer of the skin, the epidermis, where there is a defect in the skin barrier that defends us daily from external aggression.

This barrier defect is due to a quantitative and qualitative alteration of certain lipid substances (cholesterol, essential fatty acids, ceramides), which are normally placed between the keratinocytes, and a defect in filaggrin.

The outermost layer of the skin can be compared to the plaster of a wall, which only if it is intact is able to preserve the bricks from atmospheric agents.

Similarly, only if the barrier function is intact is our skin able to counter external aggression, for example from the chemicals in a detergent.

Barrier damage facilitates the penetration of irritating substances, capable of activating inflammatory and immunological processes typical of atopic dermatitis, which, as mentioned, manifests itself differently in different age groups.

Infant: the initial manifestation is a yellowish desquamation localised on the scalp, called milky scab, which when present does not necessarily imply the diagnosis of atopic dermatitis as it could only be a separate manifestation. Only the medical history could lead one to suspect atopic dermatitis if there is a family history of atopy.

First two years: eczema patches located electively on the cheeks, forehead, chin with the perioral region spared. In addition to the face, the trunk and extensor surface of the limbs may also be affected. The patches are well defined and erythematous in colour, covered with scales and serous crusts. When the dermatitis is particularly widespread, lymphadenopathy, i.e. an increase in the size of the lymph nodes, may be noted. For example, if dermatitis is present on the face, submandibular or retroauricular lymph nodes may become enlarged.

Childhood and adolescence: dermatitis patches appear on the folds of the elbows, wrists, neck, back of the ears, knees and back of the hands. Given the site, fissures, sometimes painful, may often be seen.

Adult: The affected sites are similar to the previous ones but in this case the scrotum, ankles and neck may also be affected.

Itching, an ever-present symptom in atopic dermatitis

Itching is the ever-present symptom.

There is no atopic dermatitis without itching, which if particularly intense induces the person to scratch, favouring the formation of scratching lesions but also the appearance of lichenification, a rough greyish thickening characterised by an accentuation of the physiological texture of the skin surface with a consequent loss of skin plasticity.

In addition, it can be the cause of restlessness as it can hinder a person’s sleep.

Complications

Bacterial infections are very common, but so are viral or fungal infections.

In the former case, Staphylococcus aureus can induce impetigo in atopic dermatitis patches that become moist and exudative, covered with yellowish crusts.

Herpes simplex and herpes varicelliformis are the most common causes of viral infections along with molluscum contagiosum.

Finally, with regard to fungal infections, P. ovale is responsible for the persistence of atopic dermatitis patches on the upper third of the trunk in young women.

Evolution and triggering factors of atopic dermatitis

Recurrence is the salient feature of atopic dermatitis, which tends to improve in summer and then worsen in autumn and winter, triggered by several factors

aggressive and particularly foaming detergents;
irritating clothing made of synthetic fibres or wool;
profuse sweating;
infectious episodes;
vaccinations;
dust;
stressful emotional factors.

Most people with atopic dermatitis tend to improve after puberty while still maintaining easily irritable skin.

However, between 5 and 50% of patients continue to suffer from atopic dermatitis as adults.

Therapy

Treatment is based on the severity of the disease as assessed by the prescribing physician using certain scales that consider the severity of signs and/or symptoms of the disease.

Therapy in mild forms of atopic dermatitis is topical therapy, which involves the use of emollients to soothe dry skin, cortisone or calcineurin inhibitors during the inflammatory phase, and antibiotics only if an infection is present.

Only in severe cases is systemic therapy indicated, including cortisone, cyclosporine or dupilumab.

In addition to these, phototherapy is a valuable aid in the treatment of atopic dermatitis.

A possibly European task force of specialists has drawn up the 2019 guidelines for a critical and timely approach to atopic dermatitis.

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