Orange-induced skin lesions in patients with atopic eczema: evidence for a non-IgE-mediated mechanism.

Oranges are suspected of inducing adverse skin reactions in patients with atopic eczema. We studied 21 adult patients with atopic eczema and a history of adverse reactions to oranges and 10 patients without. A dietary history, skin tests, serum IgE and oral provocation tests with oranges were obtained. Severity of eczema was monitored by SCORAD, and serum tryptase, eosinophil cationic protein and urinary methylhistamine were measured. No allergic reactions were found to orange in skin prick or patch tests. However, 23 patients (74%) had specific serum IgE to orange. Oral provocation testing resulted in pruritic eczematous or maculopapular skin lesions predominantly at the predilection sites in 16 patients (52%). The SCORAD increased significantly in patients positive to the oral provocation test (p <0.05). Specific IgE to orange did not correlate with the clinical outcome of the oral provocation test. No significant changes were found in serum mast cell tryptase, eosinophil cationic protein or in urinary methylhistamine excretion. The negative results in the skin tests and a lack of correlation between specific IgE and oral provocation tests indicate that non-IgE-mediated mechanisms are involved in cutaneous adverse reactions to oranges in patients with atopic eczema.