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.