Tolerance acquisition in solid food protein-induced enterocolitis syndrome in children

Development of a Buckwheat Allergy in a Child During Food Protein-Induced Enterocolitis Syndrome Due to Hen's Egg: A Case Report

Food protein-induced enterocolitis syndrome (FPIES) is a non-immunoglobulin E (IgE)-mediated food allergy. IgE sensitization to the causative food is often not observed, and the rate of sensitization to other common foods is not exceptionally high. This report discusses the case of a boy being followed up for FPIES due to egg yolk, who developed a buckwheat allergy during the disease. The boy was seen at the age of nine months because he vomited multiple times three hours after consuming egg yolk. Blood test results were IgE 32 IU/mL, egg white 3.78 UA/mL, and ovomucoid <0.1 UA/mL. The diagnosis was egg yolk FPIES, and a stepwise challenge test was performed; egg yolk FPIES was in remission by the age of three years. However, he developed hives after eating buckwheat when he was two years and two months old; a blood test was performed, which showed IgE 981 IU/mL and buckwheat >100 UA/mL. Initially, his condition was a non-IgE FPIES, showing that even if a patient does not have other IgE-mediated food allergy complications, it is possible to develop a new food allergy during the disease. This case demonstrates that in patients with FPIES, it is important to regularly evaluate blood tests and intake of typical causative foods for allergies.

Heterogeneity of food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy with gastrointestinal symptoms such as vomiting and diarrhea. The development of international consensus guidelines for the diagnosis and management of FPIES in 2017 enabled us to compare patients worldwide, regardless of geographic variation in disease features. As a result, it has become clear that there is heterogeneity among patients with FPIES or that there are cases that partly fit the diagnostic criteria for FPIES but have different characteristics. This review highlights the heterogeneity in FPIES characteristics in terms of trigger foods, the age of onset, differences in geographic regions, and symptoms; it further proposes four disease entities, including acute FPIES in children, acute FPIES in adults, chronic FPIES, and early-onset neonatal FPIES, depending on the age of onset and presumed pathophysiology. The major symptoms at onset and trigger foods differ in acute FPIES in children, acute FPIES in adults, and chronic FPIES, whereas the disease entities may share a similar pathophysiology. Early-onset neonatal FPIES may have a different pathophysiology than acute or chronic FPIES, and may not necessarily fulfil the full diagnostic criteria for acute or chronic FPIES described in the international consensus guidelines. Due to the similarity in symptoms, early-onset neonatal FPIES may sometimes be misdiagnosed as necrotizing enterocolitis. We aim to increase awareness of FPIES among medical staff in pediatrics, neonatology, and internal medicine and promote research, to gain a better understanding of the heterogeneity and pathophysiology of FPIES.