Food protein–induced enterocolitis syndrome

Food protein–induced enterocolitis syndrome (FPIES) is a non–IgE-, cell-mediated food allergy of unknown prevalence and pathophysiology. Onset is typically during the first year of life; seafood-induced FPIES may start in adulthood. Acute FPIES manifests within 1-4 hours after ingestion with repetitive emesis, pallor, and lethargy progressing to dehydration and hypovolemic shock in 15% of cases. Chronic FPIES manifests with intermittent emesis, watery diarrhea, and poor growth progressing to dehydration and hypovolemic shock over a period of days to weeks. Chronic FPIES has been only reported in infants aged less than 3 months fed with cow milk (CM) or soy formula. The most common triggers are CM, soy, rice, and oat. Diagnosis of FPIES relies on recognition of a pattern of clinical symptoms and may be missed owing to the absence of typical allergic symptoms (eg, urticaria, wheezing) and delayed onset in relation to food ingestion. Physician-supervised food challenge is recommended if diagnosis or the trigger food is not clear and to evaluate for resolution. Testing for food-specific IgE is usually negative, although a subset of patients, usually with CM-induced FPIES may develop sensitization to foods. Such atypical FPIES tends to have a more prolonged course. Despite the potential severity of the reactions, no fatalities have been reported, and FPIES has a favorable prognosis. In most cases, FPIES resolves by age 3-5 years, although persistence of CM-induced FPIES and soy FPIES into adulthood has been reported. The first international consensus guidelines on diagnosis and management of FPIES were published in 2017. Given that the pathophysiology of FPIES is poorly understood, there are no diagnostic biomarkers and no therapies to accelerate resolution. These unmet needs warrant future investigations to improve the care of patients with FPIES.