Allergy to peanuts and peanut oil: a new severe italian phenotype?

To the Editor, peanut allergy is one of the most common food allergy throughout Europe and USA.There are 17 registered peanut allergens in the WHO/IUIS list. Ara h 2, 6 and 7 are 2S albumins. Ara h 9, 16 and 17 are ns-LTP. Cupins: Ara h 1 and Ara h 3. PR-10: Ara h 8 (1).More recently discovered allergens are defensins: Ara h 12 and 13; Oleosins: Ara h 10, 11, 14, 15 are heat-stable and digestion resistant proteins.Both defensins and oleosins have a lipophilic structure, hence are underrepresented in aqueous extracts used in the diagnostic phase, and they can cause severe clinical reactions (2,3,4).Ara h 18, who is a recently discovered cyclophilin could carry a risk of severe symptoms and reactions (5).We present the clinical case of a female patient aged 15, with an infantile history of pruritus after peanut consumption, for which she hasn't eaten any ever since.In June 2022 she reached us seeking medical attention because after eating a lemon sorbet, on whose packaging was stated the possible presence of peanuts, she manifested pruritus, labial angioedema and dyspnea.We therefore performed a food allergen prick test which resulted positive for peanut (++++) and negative for egg (yolk and albumen), milk (alpha-lactoglobulin, beta-lactoglobulin, casein), peach, hazelnut, cod, shrimp and soy flour.Inhalant allergen prick test revealed positive for mugwort and dust mites, and negative for animal epithelia, alternaria, Gramineae, pellitory, cypress, birch, olive tree.The same day we sampled her blood for specific IgE dosage that tested negative for peanut, soy seeds, tomato, cod, apple, rice, grain, Tri a 14, Tri a19, gliadine, Pru p3, Pru p 7; positive for dust mites and negative for Art v 1 and Art v 3; total IgE resulted 49 UI/ml and basal tryptase was 3.3 ng/ml.We scheduled a prick by prick, performed with store-bought products and ALK steel lancets, with every food tested at least 10 centimeters far from the next; it resulted negative for lemon, positive for raw and roasted peanut, peanut butter, peanut oil.After a few minutes a pruriginous satellite erythema showed on her left shoulder and right scapula.In the meanwhile she had presented urticaria and difficulty in breathing while eating fried food in a fast-food restaurant, and urticaria while others were eating peanuts at her table.To exclude laboratory errors, we performed specific IgE dosage a second time, which resulted <0.10 kUA/l for peanut and its molecules (Ara h 1, 2, 3, 6, 8, 9).We additionally performed markers for celiac disease and anti-thyroid antibodies, all negative, TSH within range.We consequently prescribed auto-injectable adrenaline and trained the patient and her family to its usage and complete avoidance of peanut and its derivatives.