Atopic dermatitis in the first six months of life.

1,476/2,320 of our cases of atopic dermatitis (AD) start in the first six months of life. The diagnosis is usually easy, but at this age it is sometimes more difficult, mainly because of lack of or rare evidence of scratching, but also because of the brief clinical history that does not allow observation of the characteristic chronic and relapsing course. Moreover, the major atopic disorders-asthma, rhinitis-usually appears later in the natural history of atopic subjects. From a differential diagnosis point of view, AD is the most definite dermatological disorder at this age. Other not well defined conditions occurring in the first six months of life are usually referred to as infantile seborrheic dermatitis, a name that has been used for at least four different disorders: cradle cap, cradle cap with involvement of inguinal, axillary and retroauricular folds, napkin psoriasis and Leiner's erythroderma. From a clinical point of view, AD in the first months of life is characterized by the prevalence of exudating lesions; moreover, the lack of or the rare evidence of scratching allows us to observe isolated vesicular lesions that are found with difficulty in the further course of the disease.