Allergic colitis: a mimic of Hirschsprung disease

Background. Allergy to cow milk protein is a common cause of gastrointestin al symptoms in infancy. Milk allergy is usually a clinical diagnosis, and t hus there have been few reports of the radiographic findings. Objective. To describe the barium enema findings of allergic colitis and di fferentiate them from Hirschsprung disease. Materials and methods. Four infants (age range 7 days-5 weeks) with constip ation underwent barium enema to exclude Hirschsprung disease. Radiographic findings were correlated with the pathologic specimens from suction rectal biopsy. Results. All enemas revealed irregular narrowing of the rectum and a transi tion zone. Rectal biopsies in each case demonstrated ganglion cells and evi dence of an allergic colitis, with inflammatory infiltrates in the lamina p ropria. A diagnosis of milk allergy colitis was made and symptoms resolved after removal of milk from the diet. Conclusions. Milk allergy is common in infancy. The rectum is a primary tar get organ, with allergic colitis often diagnosed on clinical grounds alone. However, a child with allergic colitis may be referred to radiology for ba rium enema, especially if constipation is present. The radiologist should b e aware of the unique imaging findings of allergic colitis, so as to avoid confusion with Hirschsprung disease and perhaps an unnecessary rectal biops y.