D1.264 - A Case of Chronic Food Protein-Induced Enterocolitis Syndrome triggered by Egg Yolk via Breast Milk

Introduction

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal food allergy, typically manifesting as repetitive vomiting, diarrhea, and, in severe cases, hemodynamic instability. While acute FPIES is well-recognized, chronic FPIES often presents with insidious symptoms such as chronic diarrhea and failure to thrive (FTT). Most chronic FPIES cases are triggered by cow’s milk or soy formula ingestion. Although maternal ingestion of allergens can occasionally trigger symptoms in breastfed infants, chronic FPIES caused by solid food allergens, mediated through breast milk, is exceptionally rare. We report the case of an infant with severe growth retardation due to chronic FPIES triggered by egg yolk via breast milk, and acute FPIES upon direct ingestion of egg yolk.

Case Presentation

The patient was a male infant born at 39 weeks of gestation, weighing 3.0 kg. The mother consumed chicken eggs daily during pregnancy and lactation. Although the infant transitioned to exclusive breastfeeding at 4 months of age with seemingly sufficient intake, he exhibited progressive FTT. His weight was 4.9 kg (-1 SD) at 2.5 months, 5.6 kg (-2 SD) at 4.5 months, and growth plateaued thereafter, reaching only 6.2 kg (-2.8 SD) by 8 months of age, when he began consuming cooked egg yolks. While the first few ingestions were asymptomatic, the seventh ingestion resulted in severe symptoms three hours later, including repetitive vomiting, lethargy, a fever of 39℃, and profuse diarrhea, leading to an emergency referral. Laboratory findings showed serum specific IgE levels of 5.36 UA/mL for egg white and 1.68 UA/mL for egg yolk, with an elevated TARC level of 1,485 pg/mL. An oral food challenge with 5 g of cooked egg yolk was performed, which induced vomiting two hours post-ingestion, followed by somnolence and diarrhea, confirming acute FPIES.

Management and Outcome

Given the history of severe FTT during exclusive breastfeeding and confirmation of egg yolk-induced acute FPIES, we suspected chronic FPIES mediated by breast milk. We instructed the mother to eliminate all chicken eggs from her diet while continuing breastfeeding. Following this, the patient’s weight gain improved significantly to approximately 20 grams per day, and by 12 months of age, his weight had recovered to 8.5 kg (-1 SD). Based on the resolution of growth failure, the patient was definitively diagnosed with chronic FPIES of egg yolk via breast milk. Notably, he later tolerated cooked egg whites without any IgE-mediated reactions.

Discussion and Conclusion

Solid food allergens can be transmitted via breast milk in quantities sufficient to induce chronic gastrointestinal inflammation and significant growth failure. The clinical transition from chronic FTT to acute symptoms upon direct ingestion is a key diagnostic indicator. Chronic FPIES via breast milk should be considered a differential diagnosis of unexplained FTT in infants, even if they are exclusively breastfed. Early identification and maternal dietary interventions are essential for achieving rapid catch-up growth and preventing severe acute episodes.