Heavy bacterial colonization is common in all types of eczema but overt infection is most troublesome in the seborrhoeic, nummular and atopic types. Local sup-erimposed allergic reactions to medicaments can pro-voke dissemination, especially in gravitational eczema.
All severe forms of eczema have a huge effect on the quality of life. An itchy sleepless child can wreck family life. Eczema can interfere with work, sporting activities and sex lives. Jobs can be lost through it.
This falls into two halves. First, eczema has to be separated from other skin conditions that look like it. Table 7.2 plots a way through this maze. Always remember that eczemas are scaly, with poorly defined margins.
Occasionally a biopsy is helpful in confirming a diagnosis of eczema, but it will not determine the cause or type. Once the diagnosis of eczema becomes solid, look for clinical pointers towards an external cause. This determines both the need for investiga-tions and the best line of treatment. Sometimes an eruption will follow one of the well-known patterns of eczema, such as the way atopic eczema picks out the skin behind the knees, and a diagnosis can then be made readily enough. Often, however, this is not the case, and the history then becomes especially important.
A contact element is likely if:
• there is obvious contact with known irritants or allergens;
• the eruption clears when the patient goes on holiday, or at the weekends;
• the eczema is asymmetrical, or has a linear or recti-linear configuration; or
• the rash picks out the eyelids, external ear canals, hands and feet, the skin around stasis ulcers, or the peri-anal skin.