Adenomyoma of the stomach mimicking infantile hypertrophic pyloric stenosis.

We report a case of gastric adenomyoma in a 1-month-old girl. This patient presented with gastric outlet obstruction simulating infantile hypertrophic pyloric stenosis. Histologic examination of the excised specimen showed irregularly arranged glands and interlacing smooth muscle bundles surrounding the glandular elements. We suggest that this lesion is not just heterotopia, but hamartoma composed of abnormal mixture of endoderm-derived epithelial component and mesoderm-derived smooth muscle.