[Allergy investigations in eczema].

Investigation of allergy is of major importance in the diagnosis of eczema. It is mainly based on patient history: personal and familial atopic antecedents, possible contact with allergens at the work-site, in the household or during leisure activities, or in topical medications, cosmetics or clothing. Among complementary examinations, detection of eosinophilia or elevated IgE has no practical application, but sometimes the presence of specific IgE can be useful. In fact, the most important examinations are skin tests, especially patch tests, which are indispensable in contact dermatitis, and in rare cases, patch tests.