Dermatitis: the different types and how to distinguish them

By Cristiano Antonino On Jan 6, 2023

The term dermatitis is used generically to indicate an inflammation of the skin caused by various factors that trigger a skin reaction

What is atopic dermatitis?

Also known as constitutional eczema, atopic dermatitis is an inflammation of the skin, with a chronic-recurring course, that causes itching of the skin and clearly visible redness and that in Italy affects approximately 2 to 8% of the adult population.

Its presence can interfere with everyday life, worsening it considerably, as itching can compromise a good night’s rest and thus reduce concentration in study or work.

Atopic dermatitis also negatively affects self-esteem and sociality due to the frequent localisation of the disease in clearly visible areas of the skin.

Sometimes, when atopic dermatitis becomes chronic or the sufferer constantly scratches, the skin may thicken (lichenification).

It may occur (in its infantile form) as early as birth with abundant milk crust or in the first months or years of a child’s life, usually with a sudden onset.

Sudden onset may also occur in adults.

Typically, atopic dermatitis affects

hands;
feet;
inner crease of the elbow;
back crease of the knees;
wrists;
ankles;
face;
neck;
chest;
the area around the eyes.

What are the causes of the atopic form?

Atopic dermatitis has a multifactorial basis consisting of genetic, environmental and immunological factors.

People with atopic dermatitis, due to a defect in their skin barrier, come into contact with various allergens that trigger the inflammatory response.

Factors such as the change of season and psychophysical stress can exacerbate the clinical picture.

The direct cause-effect relationship between food allergens and atopic dermatitis is considered quite rare, so elimination diets, especially in children, are considered unnecessary and potentially harmful.

What are the symptoms of atopic dermatitis?

Atopic dermatitis presents with red patches (which may be covered with blisters, excoriations, crusts) on dry, itchy skin.

The itching can vary in intensity from person to person and tends to worsen overnight.

Atopic dermatitis: what tests should be done for diagnosis?

There are no specific tests for the diagnosis of atopic dermatitis, but a dermatological examination with observation of the symptoms by the specialist is usually necessary.

In some cases, measuring total IgE can help to distinguish intrinsic from extrinsic forms without, however, a significant therapeutic implication.

How is atopic dermatitis treated and how to soothe itching?

The treatment of atopic dermatitis varies according to severity.

Mild forms require topical corticosteroids, or some immunomodulators for local use, such as tacrolimus and pimecrolimus.

Where atopic dermatitis involves large areas of the skin, phototherapy may also be useful.

Taking oral antihistamines may be indicated to control itching and thus reduce scratching.

Local or systemic antibiotic therapies may be useful in case of bacterial overinfection (impetigo) of the lesions.

For more severe forms of atopic dermatitis, systemic steroids or other immunosuppressants such as cyclosporine are indicated; where the latter is contraindicated or ineffective, monoclonal antibodies such as dupilumab or tralokinumab or janus kinase inhibitors (upadacitinib, baricitinib) may be used.

To prevent atopic dermatitis, it is advisable:

Avoid excessively long and frequent baths and washes because, together with the use of more or less aggressive cleansers, they deplete the outer layers of the skin that are responsible for protection;
Dry the skin gently, patting it dry and not rubbing it;
Avoid wearing synthetic fibre clothing;
Expose yourself to the sun carefully, using specific sun filters adapted to your skin type;
Use daily moisturising-soothing creams and gentle cleansers.

Atopic dermatitis and mask use

The prolonged use of a face mask, although often necessary and appropriate, in people with atopic dermatitis can be responsible for a worsening of the skin picture.

In fact, face masks are mainly made of synthetic materials, which include allergenic substances, sanitisers and dyes that can lead to a sudden aggravation of the skin symptoms of atopic dermatitis.

In addition, having an occluding effect, they alter the skin’s microenvironment by increasing moisture and compromising its barrier function, resulting in drier skin and the risk of bacterial overinfection.

Pressure and mechanical rubbing of the mask on the skin can also create skin erosions that are particularly painful on atopic skin.

It is therefore advisable to keep the skin well moisturised, and not to hesitate to consult a dermatologist if necessary.

In general, however, good practices can be adopted to reduce the risk of skin discomfort related to the use of the mask

moisturise the skin using appropriate creams, soothing products and, if necessary, local corticosteroids (by prescription only);
use a mask of a size appropriate to one’s face, neither too wide nor too narrow. The mask should adhere to the contours of the face without exerting excessive pressure;
use non-comedogenic make-up products to avoid further occlusion of the pores.

What is seborrhoeic dermatitis?

Seborrhoeic dermatitis is characterised by an inflammation of the skin that affects areas of the skin rich in sebaceous glands such as the scalp, naso-genital grooves, retro-auricular areas, supra-ciliary arches and sternal area.

In a mild form the dermatitis manifests itself with scales that do not adhere to the scalp (known as dandruff), while in a more severe form the disease may also present with erythematous plaques covered with greasy, yellowish scales.

Seborrhoeic dermatitis is not contagious, generally occurs around 30-40 years of age and tends to become chronic (excluding neonatal and infant forms), with a greater involvement of the male sex.

What are the causes of seborrhoeic dermatitis?

The cause of seborrhoeic dermatitis is not well defined, however it is known that an excessive proliferation of yeasts of the genus Malassezia, commonly found on the skin, may be responsible for the scaling and inflammation.

Seborrhoeic dermatitis can also flare up due to certain factors, such as:

Hormonal imbalances (particularly during the change of season);
Psychophysical stress;
Genetic predisposition.

What are the symptoms of seborrhoeic dermatitis?

Seborrhoeic dermatitis typically manifests itself with:

formation of yellowish-white scales that break away from the skin (known as dandruff if present on the scalp);
skin irritation;
itching;
intense dryness of the skin.

Seborrhoeic dermatitis: what tests to do for diagnosis?

A dermatological examination should be carried out to diagnose seborrhoeic dermatitis.

How to treat seborrhoeic dermatitis?

To treat seborrhoeic dermatitis, the reproduction of Malassezia and desquamation must be counteracted: the most commonly used products are shampoos and creams based on ketoconazole, ciclopirox, selenium sulphide or salicylic acid.

Treatment with these products should be carried out more frequently when symptoms are more severe, while during periods of remission, mild shampoos suitable for frequent washing may be preferred.

Topical cortisone-based treatments may be useful in more severe forms and for short treatment cycles.

How can seborrhoeic dermatitis be prevented?

There are no specific measures to prevent the onset of seborrhoeic dermatitis.

However, it is advisable to:

avoid too frequent and aggressive bathing and washing, which risk depleting the skin’s protective surface layers;
avoid scratching and peeling the scales, so as not to feed a vicious circle of new inflammation and dermatitis;
expose yourself to the sun with due caution, as the sun’s rays can reduce inflammation.

What is allergic contact dermatitis?

Allergic contact dermatitis is an allergic skin reaction triggered by contact with chemical or natural substances that trigger an immunological response.

These substances are called allergens and when the skin comes into contact with them, an inflammatory reaction develops that causes itching.

What are the causes of allergic contact dermatitis?

Repeated contact with chemical or environmental allergens is the cause of allergic contact dermatitis.

These can be allergens:

certain metals;
dyes;
resins;
preservatives;
oils and essences of plants and flowers.

Allergic contact dermatitis can affect any part of the body, depending on the individual allergen, such as hair dye in the case of the scalp or nickel in the case of earlobes and palms.

What are the symptoms of allergic contact dermatitis?

Generally, allergic contact dermatitis has a sudden onset and manifests itself with symptoms such as

erythematous red patches
blisters;
crusts.

The rash may also be itchy.

Allergic contact dermatitis: what tests should be done for diagnosis?

To obtain a diagnosis of allergic contact dermatitis, the dermatologist can perform the patch test, an allergy test that allows the substances responsible for the dermatitis to be identified.

The test is performed by applying small traces of purified allergens to the skin to help identify what caused the allergic reaction.

The test is also useful in distinguishing allergic dermatitis from irritant contact dermatitis.

The result of the patch test is then correlated with the patient’s clinical information to assess a possible correlation between dermatitis and contact with the potential allergen.

How is allergic contact dermatitis treated?

The first step in treating this form of dermatitis is to avoid any contact with the allergen responsible for the reaction.

A cortisone-based cream may be useful to keep the rash under control.

Finally, it is advisable to wash the skin with mild detergents and to use moisturising and emollient products after washing.

How to prevent contact allergy?

The only way to prevent allergic contact dermatitis is to avoid contact with the allergens responsible for the reaction, once known.

What is irritative contact dermatitis?

Irritative contact dermatitis is an inflammation of the skin resulting from certain chemical and physical stimuli.

It usually affects areas such as the hands, neck and face, which are exposed to external contact, although a typical irritative dermatitis is nappy dermatitis, which affects the skin area covered by the nappy due to prolonged contact with faeces and urine.

What are the causes of irritative contact dermatitis?

Irritative dermatitis results from repeated and/or prolonged contact with irritating stimuli.

Among the substances that most often trigger it are:

surfactants, alcohols, antiseptics, contained in household but also personal cleansers;
solvents, acids, caustics, glass wool, especially frequent in professional contexts;
substances released by certain plants.

What are the symptoms of the irritative contact form?

Shortly after contact with the irritant or after a few hours, the skin undergoes a local inflammatory reaction.

Generally, more or less extensive reddened patches appear suddenly, and may also occur:

vesicles;
skin erosions;
desquamation;
crusts.

The rash is associated with burning/hotness or itching that leads to scratching, with the risk of promoting over-infection.

Sometimes, over time, a sensitisation may develop towards the irritant substance, which may not have given any particular problems initially, to the extent that one becomes allergic to it, resulting in allergic contact dermatitis.

What tests should be done for diagnosis?

A dermatological examination is usually sufficient for diagnosis.

Allergy tests (such as the patch test) can be used to exclude an allergic form.

How is irritative contact dermatitis treated?

In the presence of irritative contact d., soothing creams can be prescribed and, in cases with a strong inflammatory reaction, cortisone creams can be used for a short time.

How to prevent the irritative contact form?

To prevent onset and recurrence, it is best to avoid repeated and prolonged contact with irritants, although this may be more difficult to implement for those exposed to them for professional reasons.

In general, to avoid contact with the irritant agent, it may be necessary to wear gloves, preferably lined with cotton on the inside, when handling chemicals or in the case of contact with plants, and to avoid excessive hand washing, which could weaken the skin barrier and favour the penetration of irritants.

In addition, the application of emollient creams is recommended to restore lipids, removed by irritants, that contribute to the skin barrier function.

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