LAUSR

A 33-year-old woman presented with a 1-year history of dramatic lip and throat edema as well as pruritus that developed after eating various foods including tomato-based products (pizza sauce, salsa, and tomatoes), limes, lemons, and grapefruits (Fig. 1). A similar effect was noticed after using many brands of toothpaste. The patient also developed gastrointestinal distress and abdominal pain leading to nausea and occasional emesis with the above foods. Lip edema was typically followed by scaly dermatitis on the lips the following days. The patient subsequently became a coworker and was hired in the patch test clinic. She developed pruritus of the hands after each exposure to ingredients of balsam of Peru and required wearing gloves. Results of the evaluation for immunoglobulin E antibodies and skin prick tests to tomato and citrus antigens were negative. Closed chamber testing on the forearms with benzoic acid, cinnamic aldehyde, and balsam of Peru at 10 minutes produced painful and pruritic plaques, which the patient could not stop scratching (Fig. 2). Focused patch testing to those same allergens was negative although the patient noticed pruritus at the allergen sites early in the testing. The patient was diagnosed with stage 3 CU syndrome to components of balsam of Peru and was instructed to avoid foods containing balsam of Peru. Her symptoms resolved, and she remains clear as long as she avoids those foods. CU reactions are generally divided into 3 categories: nonimmunologic CU (NICU), immunologic CU (ICU), and mixed/ undetermined. NICU occurs without prior sensitization, and the causative agent theoretically triggers an urticarial reaction in most people. An example of NICU is the reaction from stinging nettles to which most people react. ICU involves type I hypersensitivity