The relevance of oral food challenge in a patient allergic to peanut and tree nuts.

Peanut allergy is one of the most common food allergies in childhood. In vitro cross-sensitization between peanut and tree nuts (TN) is high, but only a subgroup of patients allergic to peanut will have a concomitant allergy to one or several TN. In this article, the authors report a case of a 12-year-old boy who experienced 1 episode of lips and mouth itching, generalized urticarial, and eyelid angioedema 20 minutes after ingestion of peanut at 4 years of age. The immunoallergological study revealed the presence of a concomitant allergy to peanut, pistachio, and cashew confirmed with medically supervised oral food challenges (OFC) in a child who had never eaten these TN. The mechanism of IgE-mediated hypersensitivity was demonstrated by positive skin prick tests (SPT) with commercial extracts, although the specific IgE (sIgE) for these foods was negative. As described in the literature, we concluded that serum peanut and TN sIgE measurements have lower sensitivity than SPT to assess IgE sensitization, and OFC is the gold standard for accurate diagnosis of food allergy. We highlight the relevance of excluding or confirming TN allergy in a peanut-allergic patient who had never ingested certain TN, and of knowing the clinical relevant cross-reactivity patterns between TN, pistachio/cashew, and walnut/pecan, that could reduce the need for OFC in clinical practice, reducing allergy rates and financial and health burdens of food allergy.

Multiple food allergy - unexpected culprits.

Food allergy has an estimated prevalence of 6%-8% in children. Meat allergy and multiple food allergy due to sensitization to cross-reactive components in infancy is, however, less frequent. A 5-year-old girl was referred to our department with a multiple food allergy history. She had severe immediate worsening of her atopic dermatitis with hen's egg (6 months) and cow's milk introduction (7 months). At the age of 9 months, she presented with recurrent and reproducible atopic dermatitis' worsening and lip edema with the introduction of different meats (chicken, turkey, cow, pork, and rabbit), having the same complaints with fish at 12 months (salmon and hake). At her first appointment she was avoiding hen's egg, cow's milk, meat, and fish (except fresh tuna, codfish, and pollock). We performed skin prick tests (commercial extract and prick-to-prick with whole food) and specific IgE, which revealed sensitization to hen's egg, raw meat (cow, pork, chicken, turkey, duck, lamb, goat, and rabbit; negative for cooked meat), codfish and cow's milk (mild). ISAC was performed, revealing sensitization to 3 cross-reactive components (serum albumins Bosd6, Canf3, and Feld2) and specific food components of chicken's egg/meat (Gald1, 2, 3, and 5), cod (Gadc1), hazelnut (Cora9), and kiwi (Actd1). We present a rare case of multiple food allergy in infancy, where sensitization to cross-reactive components was responsible for most of the children complaints. The detection of serum albumins' involvement was especially important, because it can possibly mean tolerance to these foods in well-cooked forms, substantially improving patient and family's quality of life.