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Pathology and causes of Eczema

Atopic eczema, generally known as eczema, is a common skin disease. It can cause rashes and the skin to become very dry, itchy, and scaly. It often occurs at the same place and there may be repeated episodes. This disease usually affects children and in babies over 3 months old as their immunity system begins to develop and they may have allergic reactions to the environment. Most of the symptoms appear on the face and outer aspects of limbs. The incidence rate of eczema among children is high but the conditions usually improve in many of these patients. For children over three, the symptoms usually occurs at inner aspects of limb joints and ankles. For adults, they usually take place on the body and limbs. Though eczema will not develop into other serious medical conditions, it can result in skin infections or even sepsis if it is not managed properly.

Table 1: UK Working Party Diagnostic Criteria

An itchy skin condition (or parental report of scratching or rubbing in a child) in the last 12 months, plus three of more of the followings:

  • History of involvement of the skin creases (front of elbow, behind knees, front of ankles, around neck or eyes)
  • Personal history of asthma or hayfever (or history of atopic disease in first degree relative if child aged under 4 years)
  • A history of generally dry skin in the last year
  • Onset under the age of 2 years (not used if child aged under 4 years)
  • Visible flexural dermatitis (including dermatitis affecting cheeks or forehead and outer aspects of limbs in children under 4 years)

NB. Atopic testing such as skin prick testing or measurement of IgE does not help much in the initial diagnosis of atopic eczema.

Eczema is caused by the imbalance of helper T-cells (Th-cells) of the T-lymphocytes in the immunity system. Though we know Th-cells are the causes of eczema, we have not found out what triggers the imbalance. However, genetic factors should not be overlooked.

Researches have revealed that if one of the fraternal twins has eczema, the other has only 20 to 25% of chance of developing the disease. But if one of the identical twins has eczema, the other has 80% of chance of developing the same. This shows the close link between genetic factors and eczema. However, those with the genes may never suffer from eczema in their entire life. The medical sector has not concluded what leads to an eczema outbreak.

People with eczema may also suffer from allergic rhinitis (commonly known as nasal allergy) or asthma. This condition is known as atopic disease or allergic triad syndrome in the medical sector. But it is not conclusive. There is no evidence that unmanaged eczema will lead to allergic rhinitis or asthma.

Moreover, atopic eczema may predispose to and coexist with other dermatological disorders that may complicate diagnosis, such as hyper –IgE syndrome, scabies, herpes simplex infection (Need to consider widespread herpes simplex infection in any patient with rapidly deteriorating atopic eczema), staphylococcal and streptococcal infection, superficial fungal infection and contact dermatitis. Very rarely, it is associated with genetic disorders.

From a western medicine point of view, eczema is not curable. It can only be controlled through medications. Young patients have 50% of recovery but also 50% of relapse when they grow up. However, if treated promptly and appropriate medications applied, the condition can be managed in such a way that the symptoms will not be triggered easily, or even when triggered, the symptoms will not be too severe.

Eczema is not a serious disease but it brings much pressure to a family. It may affect the health of children and learning emotion. If there are symptoms on the face or limbs, it may have an impact on their look, which may be a blow to their confidence and mental health. This may put enormous pressure on parents. If children have any signs of eczema, please seek medical advice promptly for diagnosis and treatment. It is also important to teach children to use the right medicine and to take care of themselves so as to reduce the pressure on the family.

Key factors triggering eczema

  • High temperature; always sweating
  • Dry weather; low humidity
  • Showering too frequently or for too long; water too hot
  • Exposure to irritants like second-hand smoke, preservatives, soap, cleaning agents, fragrance added
  • Exposure to dust mites or furry animals
  • Pollen, mould
  • Wearing irritating clothes such as wool or nylon clothes
  • Emotion and pressure
  • Skin infection
  • Food allergens such as chicken eggs, cow’s milk, peanuts, wheat, soy, fish, shellfish, seafood products and nuts

The link between food and eczema has always been debated in the medical sector. Take newborn babies as an example. When they try new food, their immunity or digestive system may take time to adjust to it. The special reactions they have may not be allergic reactions. We need to work with doctors and find out in an appropriate way whether a particular food is an allergen. Another type of skin allergies is caused by contacts with allergens. The reactions in people with this allergy are not caused by food but contacts with allergens. This is contact urticaria, not eczema. The conditions are usually mild and will subside after a while.