Natural history of "intrinsic" atopic dermatitis.

Abstract

. IT is well known that allergy plays a pathogenic role in the development of atopic dermatitis (AD) (1). However, approximately 20% of AD patients suffer from a skin disease that clinically resembles the skin lesions and the distribution pattern of AD, but is not associated with atopic status. This kind of ‘‘intrinsic’’ AD (iAD) seems to differ from the classical or ‘‘extrinsic’’ form (eAD) both in the T-cell cytokine production and in the immunohistology (2, 3), but no data are available about its natural history. In this study, we investigated the persistence of AD and the development of respiratory allergic diseases in a group of children seen at the ages of 2 and 11 years according to the skin prick test (SPT) reactivity to allergens at those ages. The parents of 111 children with AD evaluated at our allergy unit in 1989–90 were asked for re-evaluation of the children about 9 years later. Seventy percent of the children (77/111) underwent clinical history, and SPTs to food (egg white, wheat, milk, tomato, codfish, and soy [Lofarma, Milan, Italy]) and inhalant allergens (dust mite, cat, dog, Alternaria, grass pollen, Parietaria, mugwort, olive pollen, and Cupressus sempervires [Lofarma]). AD was diagnosed according to Hanifin & Rajka (4). The presence of asthma and SPT reactivity was studied as previously described (5, 6). According to the SPT results, we defined the following groups: 1) ‘‘early atopic’’, i.e., those children who were already SPT positive at age 2 and were still SPT positive at age 11 2) ‘‘late-onset atopic’’, i.e., those who were negative at age 2 but became SPT positive by the age of 11 3) ‘‘nonatopic’’, i.e., those who were SPT negative at the ages of both 2 and 11. We considered patients SPT negative at age 2 as having iAD. The data were analyzed by the statistical program SPSS 6.0 for Windows with the chi-square and chi-square for trend tests. A two-sided type 1 error lower than 0.05 was considered statistically significant. Seventy-seven AD patients, with a mean age (uSE) of 24.1u2.28 months at the first evaluation, and 132u3.24 months at the second evaluation, were identified. At diagnosis, all of them had AD (77/77), 22% (17/77) had asthma, and 64% (49/77) had at least one positive SPT. At 11 years of age, 46% of them had AD (36/77), 43% (33/77) had asthma, and 84% had (65/77) at least one positive SPT. Forty-nine out of the 77 (64%) studied children had early atopy, 16/77 (21%) had late-onset atopy, and 12/77 (15%) were nonatopic. None of the nonatopic children developed asthma by age 11 (0/12), compared with the 25% (4/16) and the 59% (29/49) of the late-onset and early atopic children, respectively (chi square for trend, P,0.0002). AD was still present by age 11 in 67% (8/12) of nonatopic AD as compared with 44% (7/16) and 43% (21/49) of the late-onset and early atopic children (Fig. 1). Altogether, the 28 AD children ALLERGY 2001: 56 :452^463 . COPYRIGHT G MUNKSGAARD 2001 . ISSN 0105-4538 . ALL RIGHTS RESERVED . CONTRIBUTIONS TO THIS SECTION WILL NOT UNDERGO PEER REVIEW, BUT WILL BE REVIEWED BY THE ASSOCIATE EDITORS .