Psoriasis and allergic contact dermatitis (ACD) have long been considered to be mutually exclusive conditions.
Methods: During a retrospective analysis of 186 consecutive patients who underwent comprehensive patch testing at the University of Miami from December 2004 to December 2006, we did a subanalysis of the 15 psoriatic patients who had undergone patch testing. All of the psoriatic patients were referred for worsening chronic plaque psoriasis because of suspected ACD. These patients' results were compared with an age- and gender-matched comparison group with chronic dermatitis and no self or family history of autoimmune diseases (including psoriasis).
Results: We found that the 15 psoriatic patients all had clinically relevant allergens identified during patch testing to the North American Contact Dermatitis Group standard screening series and supplemental allergen panels based on history. In the psoriasis group, 75% of the top 12 allergens were found to be associated with personal hygiene regiments or topical treatments. The top 4 allergens in both groups were nickel sulfate, cocamidopropyl betaine, balsam of Peru, and methyldibromoglutaronitrile.
Conclusion: We conclude that patients with psoriasis are capable of having concurrent ACD and their therapeutic products are a frequent source of allergens.