Pyloric narrowing with increased fibrous tissue of the mucosa in an infant.

An infant with pyloric narrowing following bilious vomiting is described. Barium meal studies demonstrated fixed narrowing of the pyloric canal similar to infantile hypertrophic pyloric stenosis. However, sonographic examination failed to prove significant muscular hypertrophy of the pylorus. Histology of the pre-pyloric mucosal biopsy specimens showed nonspecific inflammation with increased fibrous tissue of the mucosa. Repeated histological examination revealed regression of mucosal inflammation; the patient became symptom free and normal growth was confirmed at 2 years of age. It is possible that antral/pyloric mucosal inflammation, the pathogenesis of which remains unclear, was the cause of pyloric narrowing and then led to nonbilious vomiting.