Clinical differences between atopic and atopiform dermatitis.

BACKGROUND: Atopic dermatitis (AD) has been divided into the "extrinsic" and "intrinsic" type, in which "intrinsic AD" is characterized by the absence of allergen-specific IgE. Still, there is no consensus whether this "intrinsic type" of AD, which we denominate as atopiform dermatitis (AFD), is a distinct entity.

OBJECTIVE: A case-control study was performed to compare the clinical and diagnostic features of AD and AFD.

METHODS: Patients with a clinical diagnosis of AD were selected. Cases did not have demonstrable allergen-specific IgE. Matched control subjects were tested positive for allergen-specific IgE. Patients were evaluated for medical history, quality of life, disease severity, and Hanifin and Rajka, U.K. and Millennium diagnostic criteria.

RESULTS: Eight percent (n = 34) of the selected patients had, in fact, AFD. Female predominance, absence of atopic diseases, later onset of disease, and milder disease severity were observed in AFD. A history of atopy, recurrent conjunctivitis, palmar hyperlinearity, keratosis pilaris, pityriasis alba, and hand and/or food eczema were significantly less present in AFD. Dennie-Morgan fold was positively associated with AFD.

LIMITATIONS: Not all patients with negative allergen-specific IgE participated and a relatively small number of AFD patients were studied.

CONCLUSIONS: In addition to the absence of allergen-specific IgE, our findings support that AFD is an entity distinct from AD. With a distinction shown between AFD and AD, patient groups will be better defined and more homogeneous. Implications of this distinction will be of importance for preventive and therapeutic advice; diagnostic processes; and for future research.