Broad Bean-Induced Anaphylaxis: A Case Report.

Broad bean (Vicia faba) is a herbaceous climbing plant that can self-pollinate and grow in any type of soil. It is now cultivated throughout the world and commonly used in cooking. Vicia faba belongs to the Fabaceae family and comprises 3 distinct varieties: Vicia faba var minor, Vicia faba var equina, and Vicia faba var major, which is the most widely eaten. Broad beans are eaten raw, cooked, or fried and have recently been used as flour in various kinds of bread [1]. Allergic reactions to broad beans have rarely been reported in the literature [1,2]. Cross-reactivity has been reported between pollen of the mesquite tree (Prosopis juliflora) and some legumes, such as broad beans [3]. Food processing can denature proteins or create new epitopes, thus modifying allergenicity [4]. For example, roasting can increase the allergenicity of peanut proteins [5] and reduce the allergenicity of hazelnut and almond proteins [6]. Combining heat and digestion by pepsin in broad beans can slightly reduce immunoreactivity [7], as reported with tomato [8]. Most in vitro studies on the allergenicity of nonspecific lipid transfer proteins and seed storage proteins show that the proteins are thermostable when subjected to thermal processing methods [9]. However, the role of lipids as the allergens responsible for the reactions is increasingly well-known [10]. We report the case of a 5-year-old boy with no previous history of allergy who developed cough, dyspnea, auricular erythema, papules on the trunk, abdominal pain, nausea, and vomiting 2 hours after dinner. The symptoms disappeared several hours after treatment with adrenaline, antihistamines, and corticosteroids in the emergency department. Immediately before dinner, he had eaten a legume-based snack containing pistachio, peanuts, sunflower seeds, hazelnuts, almond, pine nuts, and fried broad beans. Between the episode and the first visit to the allergy clinic the child avoided tree nuts. He did not experience further episodes. Skin prick testing was negative with extracts from pistachio and walnut (Bial-Arístegui), peanut, and almond (Leti) and positive with hazelnut (7×3 mm), sunflower seeds (6×3 mm, Bial-Arístegui), and pine nut (8×4 mm, Leti). Skin prick testing was also positive with Pru p 3 (10×5 mm) and negative with profilin from Phoenix species pollen. Prick-by-prick testing was negative with roasted peanut, almond, and sunflower seeds and positive with cooked, raw, and fried broad beans (6×4 mm, 7×3 mm, and 6×3 mm, respectively). Skin prick tests were negative with commercial extracts from dander (dog and cat), molds, mites, and pollen (grass, olive, and pellitory) and was positive with pollens from Platanus species (3×4 mm), mugwort (3×4 mm), Plantago species (3×4 mm), Chenopodium species (4×4 mm), and ash (3×3 mm). The histamine wheal diameter was 7×5 mm. Blood tests using the ImmunoCAP assay (Phadia) revealed total IgE of 119.0 kU/L and specific IgE determinations (kUA/L) of 4.97 to peanut, 2.85 to hazelnut, 16.1 to walnut, 8.55 to sunflower seeds, and 0.64 to almond. Serum specific IgE was positive to Ara h 9 (23.2 kUA/L), Cor a 8 (6.72 kUA/L), and Pru p 3 (27.4 kUA/L) and negative for Ara h 2 (0.01 kUA/L). Specific IgE to fried broad beans determined using the enzyme allergosorbent test (HYTEC Specific IgE EIA kit, HYCOR Biomedical Ltd) was 0.8 kUA/L (class 2).