When the disease is due to endogenous factors, it is divided into:
- Atopic Dermatitis/Eczema or infantile eczema: Chronic inflammatory skin condition of unknown etiology, with a hereditary predisposition in 70% of cases, occurring mainly during childhood. People with Atopic Dermatitis are more often affected by food allergies, asthma, rhinitis, urticaria, and are more susceptible to staphylococcal and viral infections. Although the etiology is not known, aeroallergens and food allergens have been found to play a role, as well as genetic factors. Atopic Dermatitis affects both children and adults and occurs mainly as erythema with itching and scaling in the flexural folds e.g. behind the knees and on the elbows. The incidence in childhood is up to 20%. There is almost always itching, as well as dry skin. Atopic Dermatitis has periods of remission, while sometimes it disappears completely for a long period of time.
- Seborrheic Dermatitis: Occurs frequently in both adults and infants. The fungus Malasezia furfur or Pityrosporum ovale plays a role in the etiopathogenesis of the disease. In infants it presents as reddish-yellow plaque-forming scales and in adults as redness, scaling and itching in areas rich in sebaceous glands such as the scalp, eyebrows, nose flaps, sternum and back. The rash in these areas is red, scaly and itching-free. Exacerbations of the disease occur mainly in winter and during periods of stress. It appears in the form of red scaly plaques on the face, nose and above the eyebrows. Examination of the scalp often reveals sticky scales on the contour of the hair. Sometimes there is a rounded plaque in the middle of the sternum. Furthermore, the facial skin is easily irritated and itching appears on the scalp. Seborrheic dermatitis should be distinguished from scalp psoriasis which often shows a similar picture.
- Coin Eczema: Characterized by circular, coin-like, red plaques and is mainly found on the upper limbs and chest. It occurs mainly in areas where the skin has been irritated, but this is not the only occurrence. Symptoms usually include itching and burning sensations, with the possibility of an increase in symptoms during the evening hours. Eczema of this type starts as a group of tiny and reddish spots, and bubbles of fluid may also be present. Many times, the likelihood of developing coin eczema is increased in people with dry skin or Atopic Dermatitis, as well as in people with circulatory disorders. In the case of this type of eczema, hydration and topical administration of corticosteroids and antihistamines are recommended.
- Dyshidrotic Eczema: Dyshidrotic eczema is a recurrent form of vesicular dermatitis and is thought to develop due to a reaction to a variety of endogenous and exogenous factors, such as heat, stress or fungal infection of the feet, as well as overreaction to existing inflammation from fungi or genetic predisposition. Dyshidrotic Eczema in 50% of cases occurs in people who have previously developed atopic dermatitis or in people who have a family history of eczema. A fairly important factor in the development of this eczema is sensitivity to metals such as nickel and cobalt. This fact suggests an association between dyshidrotic eczema and allergic contact dermatitis, which will be discussed below. Dyshidrotic Eczema can be self-limited, or chronic and its severity ranges from mild to very severe. It is a symmetrical rash that occurs mainly on the palms and soles. Often, blisters develop followed by drying and scaling. It is characterized by intense itching or burning sensation and often cracks may form in the skin. Dyshidrotic Eczema occurs more often in hot countries and usually affects a higher percentage of women than men. It is called dyshidrosis because its main characteristic is the dysfunction of the sweat glands and studies have shown that hyperhidrosis can cause dyshidrosis eczema to develop.
In case the eczema is due to factors of exogenous etiology, dermatitis is divided into:
- Irritant contact dermatitis: Irritant contact dermatitis causes inflammation of the skin by the effect of agents that act as irritants on the skin for a short or long period of time, and is divided into acute and chronic forms. In the acute form there is partial destruction of epidermal cells and activation of T-lymphocytes. Chronic irritant dermatitis is usually caused by more than one factor. Indicatively, exogenous causes of the disease may include water, detergents, cleaning agents, building materials and plant substances (e.g. tomato, onion, oils). When the dermatitis is severe there may be pain and severe inflammation with exudate (fluid). During the chronic phase of dermatitis, i.e. when the irritant is active for more than 2 months, there is thickening of the skin with an increase in normal folds, dryness, itching and hyperpigmentation, a condition called lichenification.
- Allergic contact dermatitis: It is a hypersensitivity reaction and is caused by the contact of the skin with certain substances (chemical or natural), with the involvement of immune mechanisms and is due to hypersensitivity of the skin to irritants. These irritants, or allergens, are agents to which the skin has previously been sensitised. Erythema may occur at or away from the area of contact. Such irritants include nickel (e.g. coins), resins, cosmetic ingredients, cement, topical pharmaceuticals and certain plants (e.g. chrysanthemum). Nickel, in particular, is the most common cause of dermatitis in this category. It is found in many everyday products, such as jewellery, cutlery and even in clothing clasps. Although dermatitis can be normalised by the use of corticosteroid preparations, the best treatment is to avoid contact with nickel-containing objects. Especially people who are highly sensitive should avoid nickel-containing foods such as chocolates, oats and nuts.
The severity of the allergenic action depends on the properties of the allergen, the duration of contact, and the host skin response. Usually, vesicle formation is observed, which may swell and rupture. Because allergic dermatitis may have similar clinical symptoms to other dermatological problems, the correct cause of the symptoms must be identified so that appropriate treatment can be followed.
Other, rarer, forms of eczema are asteromatous, stasis dermatitis and localised neurodermatitis. Asteroidal eczema is caused by dehydration of the skin, up to 75% compared to healthy skin. The likelihood of its occurrence is higher in men over the age of 60, although it rarely occurs at a younger age.
