Urticaria due to acitretin in a patient with lichen planus

Sir, Acitretin is a synthetic retinoid used in the treatment of many dermatologic diseases such as psoriasis, keratinization disorders, cutaneous T-cell lymphoma, and lichen planus. Carcinoid syndrome, insect bite, mastocytosis, food allergy, histamine poisoning, latex allergy, ethylene oxide/chlorhexidine allergy, infections (infectious mononucleosis, hepatitis, and parasites), and pseudoallergic reactions should be considered in the differential diagnosis of immediate-type (immunoglobulin E-mediated) drug reactions. [...]studies are warranted in order to determine the pathogenesis of allergic reactions to retinoids.