Pyloric stenosis caused by noncystic duodenal duplication and ectopic pancreas in a neonate.

Abstract

Pyloric stenosis caused by gastrointestinal duplication is an extremely rare condition in neonates and young infants; only a few cases have been reported (1-4). Histologic evaluation revealed gastric duplication in all cases except one, which involved a pyloroduodenal duplication (5). Pyloric stenosis in all of the cases was caused by cystic formation of gastroduodenal duplication with no exceptions. In the case we report, an upper gastrointestinal barium study (UGI) accurately indicated pyloric stenosis caused by a submucosal mass on the pylorus. Pathologic evaluation confirmed a noncystic duodenal duplication and ectopic pancreatic acinar tissue. CASE REPORT A 1-week-old male infant was admitted for investigation of nonbilious projectile vomiting. On physical examination, his abdomen was soft with no palpable masses. Ultrasonography (US) showed a hypertrophic pyloric muscle with a thickness of 3.7 mm. Atropine sulfate, at a dose of 0.04 mg/kg/day was administered for 1 week. A UGI study revealed pyloric stenosis caused by a submucosal mass of the pylorus (Fig. 1). Surgical exploration showed a submucosal solid mass of 10 × 10 mm in diameter located on the greater curvature of the pylorus. It was excised in an extramucosal fashion. Histologic evaluation confirmed pyloric muscle with non-cystic duodenal duplication and ectopic pancreatic acinar tissue(Fig. 2). The postoperative clinical course was uneventful.FIG. 1: Upper gastrointestinal barium study showing gastric outlet obstruction and a 10-mm in diameter submucosal mass of the pylorus (a semiprone view).FIG. 2: Microscopic appearance of an excised submucosal mass. Hematoxylin-eosin; magnification, ×50. Pyloric muscle with ectopic pancreatic acinar tissue (open arrow) and noncystic duodenal duplication (filled arrow).DISCUSSION Gastrointestinal duplication on the pylorus is an extremely rare condition. The first case of pyloric duplication cyst was reported by Ramsay in 1957 (2). Additional cases of pyloric, gastropyloric, or pyloroduodenal duplication have been reported (1,3-6) in which gastric outlet was obstructed by a duplication cyst. In our case, the gastric outlet was obstructed by a small submucosal mass, which consisted of pyloric muscle, duodenal duplication without a cystic lumen, and ectopic pancreatic acinar tissue. Grosfeld et al. (3) reported gastric duplication with pancreatic acinar tissue; however, noncystic duodenal duplication with ectopic pancreatic tissue has not been reported in the English literature. The diagnosis of pyloric duplication is based on clinical symptoms that generally mimic those of hypertrophic pyloric stenosis. Recently, ultrasound has provided an accurate measurement of the thickness of pyloric muscle. It also provides indication for surgical pyloric myotomy in most of the patients with hypertrophic pyloric stenosis, (7) thus rendering UGI unnecessary. Although UGI may show only pyloric narrowing and may not demonstrate the duplication, correct preoperative diagnosis of pyloric duplication has recently been achieved by ultrasound(4). However, when the duplication is small and noncystic, UGI may demonstrate a solid mass as the cause of gastric outlet obstruction, as was seen in our case.