Food Protein-Induced Enterocolitis Syndrome in a Breastfed Infant

Background: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that occurs following the ingestion of a triggering food. Symptoms include incoercible vomiting and diarrhea 1-4 hours post exposure, and in severe cases dehydration and shock. This rare condition usually presents in infants younger than 9 months, with cow’s milk protein (CMP) as the main trigger. Breastfed infants seem to be protected against CMP-FPIES, although a few cases have been reported with exclusive breastfeeding. Diagnosis is clinical relying on a high suspicion.

Clinical Case: A 2-month-old girl exclusively breastfed (except for single bottle of regular formula at day-1) was admitted with intermittent bloody and mucous diarrhea, significant weight loss and dehydration. Laboratory findings showed hypoalbuminemia, thrombocytosis, mild hyponatremia and metabolic acidosis. Breastmilk was replaced by a semi-elemental formula (SEF), with clinical improvement. Once breastmilk was reintroduced the symptoms recurred. The infant was kept on a CMP free diet with regular growth and no gastrointestinal symptoms. A first oral food challenge (OFC) to CMP was performed around 9 months and was positive. Last OFC at 36 months remained positive. Diagnosis of FPIES caused by CMP passed through breastmilk was established. Currently, at age 4, she continues to thrive well under CMP restriction.

Discussion: Assessment of FPIES is difficult since it’s an exclusion diagnosis. Our case enlightens the importance of considering this condition whenever typical symptoms ensue, even in exclusively breastfed infants. Misdiagnosis or delayed diagnosis are common and may lead to a critical life-threatening situation.