Allergic contact dermatitis from hydrangea--is it so rare?

8 cases of allergic contact dermatitis from hydrangea seen in Angers, France, during the last 15 years are reported and compared to other cases found in the literature. In this review, allergic contact dermatitis from hydrangeas appears to be an occupational dermatosis among nursery workers, presenting as an eczema involving the hands and especially the first 3 fingers, with chronic features of fissuring and scaling and with a chronic course. Differential diagnosis from irritant contact dermatitis may be difficult. Patch tests with the stem as well as the leaf of hydrangeas gave strong positive reactions in all patients, and hydrangenol, the allergen of hydrangea, when tested, always also gave a positive reaction. Sensitization seems to occur after close and prolonged contact with the plant, which could explain the relative frequency in Angers because it provides almost 90% of hydrangea seedling production in France.