Allergic colitis : a mimic of Hirschsprung disease

Allergy to cow milk protein is a common cause of gastrointestinal symptoms in infancy. Milk allergy is usually a clinical diagnosis, and thus there have been few reports of the radiographic findings. To describe the barium enema findings of allergic colitis and differentiate them from Hirschsprung disease. Materials and methods. Four infants (age range 7 days-5 weeks) with constipation underwent barium enema to exclude Hirschsprung disease. Radiographic findings were correlated with the pathologic specimens from suction rectal biopsy. All enemas revealed irregular narrowing of the rectum and a transition zone. Rectal biopsies in each case demonstrated ganglion cells and evidence of an allergic colitis, with inflammatory infiltrates in the lamina propria. A diagnosis of milk allergy colitis was made and symptoms resolved after removal of milk from the diet. Milk allergy is common in infancy. The rectum is a primary target organ, with allergic colitis often diagnosed on clinical grounds alone. However, a child with allergic colitis may be referred to radiology for barium enema, especially if constipation is present. The radiologist should be aware of the unique imaging findings of allergic colitis, so as to avoid confusion with Hirschsprung disease and perhaps an unnecessary rectal biopsy.