Eczema is a skin condition characterized by inflammation, itchiness and discharge. There is no one systematic classification of various types and forms of eczema. While one classification uses the location to describe eczema like hand eczema another describes it by appearance (e.g. eczema craquele or discoid eczema). Yet another classification describes eczema by possible cause allergic or atopic eczema or varicose eczema. The terms atopic eczema and eczema are often used interchangeably.
The nomenclature for various forms of allergies was first decided upon in a 2001 position paper published by the European Academy of Allergology and Clinical Immunology (EAACI). This paper simplified the nomenclature of dermatitis associated with allergies including eczema. Non-allergic eczemas were not included in the paper.
Types of eczema commonly encountered include:-
Atopic eczema
This is also called the infantile eczema as it affects babies more commonly. It is also known as atopic dermatitis. This is usually inherited and may have a genetic component. Hay fever and asthma is a common co-morbidity with this type of eczema. It usually affects the head and scalp, folds of the neck, crook of the elbows, behind knees, and folds of the thighs and buttocks. At times atopic dermatitis may be confused with irritant contact dermatitis. It is very common in developed countries.
Contact dermatitis
This is of two main types – allergic due to an allergic reaction to an allergen (e.g. poison ivy or nickel) and irritant contact dermatitis due to direct abrasion and skin damage by chemicals, detergents, sodium lauryl sulphate in soaps, creams etc. Sometimes a single substance may act both as an allergen and an irritant on skin. Other substances may cause skin damage after sunlight exposure, and lead to phototoxic dermatitis. This is a curable condition.
Xerotic eczema
This is also known as craquele or craquelatum, winter itch, pruritus hiemalis or asteatosis form of eczema. This is caused due to dry skin that becomes so serious it turns into eczema. This commonly affects the trunk and limbs. This condition may worsen during dry winter months. The skin becomes dry and cracked. This disorder is very common among the older population. Ichthyosis is a related condition.
Seborrhoeic dermatitis
This is also termed cradle cap as it affects infants. The condition is closely related to dandruff. It causes dry or greasy peeling of the scalp, eyebrows, and face. The back may also be affected. It is usually harmless and may lead to loss of hair. In newborns it causes a thick, yellow crusty scalp rash called cradle cap. The condition is curable.
Discoid eczema
This is also called nummular, exudative or microbial eczema. There are spots oozing secretions or dry rash, with clear boundaries, often on lower legs. It is usually worse in winter. This is a relapsing condition.
- Dyshidrosis or pompholyx, vesicular palmoplantar dermatitis This is commonly called housewife’s eczema and affects palms, soles, and sides of fingers and toes. The lesions appear as small vesicles or bumps, thickening, and crack in the affected areas along with itching. The itching gets worse at night. This may worsen in warm weather.
- Dermatitis herpetiformis
This is also called Duhring’s Disease and it causes a symmetrical rash on arms, thighs, knees, and back. It is seen in persons with celiac disease and can be treated with appropriate diet.
Venous eczema or varicose eczema
This is seen in persons with varicose veins and thus commonly affects lower limbs around the ankles. There is redness, scaling, darkening of the skin and itching. This may be precursor of leg ulcers.
Autoeczematization or autosensitization
This is eczema seen when infected with parasites, fungi, bacteria or viruses. It is completely curable with the clearance of the original infection.
Neurodermatitis or lichen simplex chronicus
This is localized scratch dermatitis that is seen as an itchy area of thickened, pigmented eczema patch. It occurs due to regular rubbing, pressure or scratching a particular area. Prurigo nodularis is a related condition.
Further Reading
Can your baby's gut bacteria predict food allergies?