[Allergic colitis: clinical and morphological aspects in infants with rectal bleeding].

Background: Recent studies indicate the importance of eosinophilis infiltrated in the rectal mucous which jointly with the clinical features can serve to establish the diagnostic of allergic colitis.

Aim: To describe prospectively, the clinical features and morphological abnormalities of the rectal mucosa in patients with rectal bleeding and clinical diagnosis of cow's milk allergy.

Methods: Clinical features of 20 infants under 6 months of age were described. Morphological findings in rectal mucosa were compared with control group, with suspicion of congenital megacolon.

Results: The mean age of the patients was 97 +/- 47 days, rectal bleeding started before 120 days in 85% of them; 40% were breastfed, 60% cow's milk formula or both. The most striking morphological feature, in 18 patients, was eosinophilic infiltration in the rectal mucosa. There was a significant statistical difference when these values were compared with control group.

Conclusions: The increased number of eosinophils in the rectal mucosa represent the most important characteristic of allergic colitis, in patients under 6 months, with rectal bleeding, when breastfed, cow's milk formula or both.