Food allergy and intolerance
Food allergy, which is immunologically mediated, and food intolerance, caused by direct histamine release, are not common exacerbating factors in AD but they can be very relevant in some patients. It is common for parents to request allergy testing. Often they have good reason to do so, having observed their child’s reactions to certain foods – particularly cow’s and soy milk, peanuts, eggs, shellfish and high salicylate foods such as tomatoes and fresh fruits. However, misinformation on the internet leads many to believe that AD is an allergy in itself and to hold high hopes that if they can discover and eliminate the allergen(s) that a cure will result. This is rarely the case.
Dermatitis and psoriasis
The coexistence of dermatitis and psoriasis is not uncommon when AD seems more difficult than usual to control or never completely responds to topical corticosteroids (Figure 4). Both are common skin conditions. Psoriasis in young children is much more subtle than that in adults, and the classic thickened plaques rarely occur. When AD and psoriasis occur together a clinical picture termed ‘psoriasiform dermatitis’ applies.2 These children have features of both; however, their condition is usually much more treatment resistant than children with AD only and requires specific psoriasis therapy.
Parents should be asked about the family history, and signs of psoriasis in the child and parents looked for – for example, scaling of scalp and postauricular skin, or cracking under the earlobe and nail pits. Scaling, lichenification and papules on the dorsal surface of the knees and elbows in combination with dermatitis on the ventral surface is common and rarely looks like a typical psoriatic plaque seen in an adult.
Dermatitis and symptomatic dermographism
When children with apparently mild or well-suppressed eczema experience itch out of proportion to their clinical signs, they may have coexistent symptomatic dermographism. Dermographism is a form of chronic inducible urticaria. In this condition, histamine is easily released from mast cells in skin as a result of minor friction such as scratching or overheating. It can uncommonly be associated with allergy. Dermographism is easy to diagnose simply by firmly stroking the skin. This will result rapidly in a red wheal which takes 10 to 20 minutes to resolve (Figure 5). Although in general antihistamines are unhelpful in treating AD other than acting as night-time sedatives, they are useful in this subgroup.
Psychological problems and other pressures
Psychological problems are more often seen in children who are severely affected with AD, and the impact on quality of life should never be underestimated. An Australian study has shown that severe AD is as impactful as other severe paediatric conditions such as diabetes and epilepsy.3
The most common problem is exhaustion from not sleeping well, leading to behavioural problems and poor concentration at school. However, the management of AD can come to dominate the child’s and parents’ lives, and it is common for any child with a chronic condition to become weary of the daily routine of treatment and to complain, fight, abscond and resist. Many parents are also exhausted, and, in the worst cases, outright rejection of the child by the parents may ensue.