Myoepithelial hamartoma of the duodenal wall.

A rare case of myoepithelial hamartoma of the duodenal wall is presented, and previous case reports found in the literature are reviewed. Myoepithelial hamartomas are thought to arise from displaced pancreatic anlage present along the gastrointestinal tract during embryogenesis, which can differentiate into various pancreatic elements; the most highly differentiated form is heterotopic pancreas. An alternative theory is pancreatic metaplasia of endodermal tissues. We describe a 41-year-old man who presented with abdominal pain and vomiting. CT scanning revealed a mass at the head of the pancreas. A pancreaticoduodenectomy was performed for presumed cystadenoma. Histology of the mass revealed a disorderly arrangement of smooth muscle, dilated and nondilated ducts, pancreatic acinar tissue and mucus glands. The relationship of myoepithelial hamartomas involving the small bowel to similar lesions in the stomach, bile ducts and gallbladder is discussed.