The authors describe three cases of infants (aged from 45 days to 6 months) who presented profuse rectal bleeding starting at the age of 1–3 months, when still fed exclusively on mother’s milk. This symptom continued even though the mothers began to observe a strict diet free of cow’s milk proteins. In all cases colonoscopy revealed colonic mucosa that was red, edematous and friable with widespread erosive lesions. Mucosal biopsy specimens revealed intra-epithelial eosinophilic granulocytes and a widespread increase of lymphomonocytes in the lamina propria. Laboratory tests were normal except a marked anaemia. While prick tests for cow’s milk protein and RAST proved negative, the patch test carried out with cow’s milk and mother’s milk was clearly positive in all cases. The possibility of viral and bacterial infections capable of accounting for the endoscopic findings was ruled out. The rectal bleeding cleared up in 4–5 days after the replacement of maternal milk with a formula consisting of amino acids (Neocate, Nutricia). The second endoscopy, carried out 15 days after the first, showed a normal mucosa except the persistence of slight erythema.
Conclusion These cases appear to bear out the hypothesis that in breast-fed children, even at an early age, the foodstuffs passed on through maternal milk can lead to severe enteropathy mediated by a delayed type of immunological mechanism. The patch test in the absence of immunological mechanisms of reaginic type, as in our cases, can prove a simple and useful aid in arriving at the diagnosis of food allergy.