IgE sensitization
IgE sensitization to the culprit food was found in 28/180 FPIES (14.7%). Skin prick tests with the offending food were performed in 121/192 cases (63.0%) and were positive in 5 cases (4.1%). One child developed an IgE-mediated allergy with the culprit food over time: she had a confirmed typical FPIES to CM until the age of 3 without any sensitization, and had thereafter developed an immediate urticaria and rhinoconjunctivitis after ingestion of CM at 5 years old, with a positive SPT and increased CM’s IgE: 10.9 kU/L. By contrast, a child with a history of IgE-mediated allergy to CM during the first year of life (urticaria after cow’s milk ingestion and specific CM’s IgE: 4.9 kU/L at the age of 1 month), switched to FPIES to CM after 9 months of age. Her specific IgE was negative at this time, and she had repetitive vomiting, without skin or respiratory symptoms, during an OFC to CM at the age of 10 months.