Atopy and contact sensitization in psoriasis.

The allergen-specific IgE antibody was determined in 20 men and 120 women with psoriasis and the results were correlated with a history of current and previous allergic disease. Allergic disease was reported in 21% of the patients, but a positive RAST test was obtained in 44%. In chronic plaque-type psoriasis a positive RAST test was significantly more common (58%) than in active psoriasis (22%). Grass pollen and house dust mite were the most prevalent sensitizing allergens, with frequencies of 64% and 53%, respectively in the sensitized subjects. Sensitization increased with age and polysensitization was common. Contact dermatitis was verified with patch tests in 12 men and 20 woman, of whom 10 had chronic plaque-type psoriasis and 22 active psoriasis. Tar, nickel sulphate, corticosteroid mixture and thiomersal were the most common allergens. No irritant reactions were seen at the concentrations used. Atopic allergic diseases and contact sensitization were therefore common among our psoriatic patients.