Maternal diet: Exclusively breastfed infants react to maternal ingestion of cow’s milk (most common, ~60%), soy (second most common), egg, or corn.
Formula-fed infants: React to intact proteins in standard cow’s milk or soy formula.
Associated with a personal and family history of atopy
Clinical features
Well-appearing infant (normal weight gain, non-distended abdomen, no systemic signs of illness).
Painless, bloody stools (streaks of blood and/or mucus mixed w/ normal stool). c
Occasional mild spitting up or loose stools, but overall infant remains healthy.
Histopathology findings include infiltration of eosinophils within the lamina propria and muscularis mucosa.
Treatment
First-line:
Breastfed infants:
Maternal dietary elimination of cow’s milk protein and soy.
Symptom resolution typically occurs within 72-96 hours (up to 2 weeks for complete resolution).
Formula-fed infants:
Switch to an extensively hydrolyzed formula.
Second-line:
If symptoms persist in breastfed infants despite maternal dairy/soy restriction: Eliminate other potential triggers (e.g., egg, corn, wheat).
If symptoms persist in formula-fed infants on hydrolyzed formula: Switch to an amino acid-based (elemental) formula.
Long-term / Refractory:
Maintain dietary elimination until 12 months of age or at least 6 months after diagnosis.
Gradual challenge: Reintroduce offending protein (e.g., CMP/soy) to the maternal diet or infant’s direct diet after age 1, as the vast majority of cases spontaneously resolve.