Prepyloric web is a rare diagnosis in pediatrics. The prevalence is unknown: only sporadic cases are described in the literature (1–6). The clinical manifestation of prepyloric web depends on the degree of the gastric outlet obstruction, the consistency of ingested food, and the ability of the gastric motility to overcome the partial luminal web (1). Usually, incomplete antral membranes are diagnosed at an older age (3–11 years) and exceptionally in adulthood (7,8). In this case report, we conclude a deceptive presentation of prepyloric web with prominent pulmonary symptoms disguising gastric outlet obstruction. Finally, in this case, the clue to the diagnosis was a combined diagnostic gastroduodenoscopy and laparoscopic procedure.
A 5-year-old girl was admitted to our tertiary care hospital with a long history of coughing and vomiting. In infancy, the patient was diagnosed in a local hospital as having bronchial hypersensitivity and treated with inhaled corticosteroids recommended by the pulmonologist in our hospital. Cystic fibrosis was excluded by the performance of a sweat test. In the first year of life, repeated oral antibiotic treatments were given for recurrent bouts of pneumonia that persisted until the age of 2 years, and repeated chest x-rays showed a persistent atelectasis of the right upper lung. Bronchomalacia, primary ciliary dyskinesia, and asthma as causes of middle lobe syndrome (characterized by right middle lobe atelectasis) were considered by the pulmonologist. A bronchoscopy showed a normal anatomy of all of the bronchial branches with stationary cilia in the fresh bronchial biopsy. Cross-sections of the biopsy material were examined by electron microscopy; however, no primary ciliary dyskinesia-specific defects of the ultrastructure were found. Owing to the young age of the patient (younger than 5 years), an additional exhaled nasal nitric oxide test, decreased or absent in patients with primary ciliary dyskinesia, was not performed.
In conjunction with the pulmonary complaints, progressive feeding problems developed. At the age of 9 months, the patient was admitted to the local hospital because of severe dehydration caused by persistent diarrhoea. Because the condition of the patient and the existing diarrhoea did not recover after rehydration, the patient was referred to our hospital and parenteral feeding was administered for 2 weeks. During this period, enteral tube feeding was gradually reintroduced. After the acute episode, continuation of enteral tube feeding was needed for 1.5 years because of the persistent feeding problems and vomiting. During this time, no effort was made to understand why the patient presented with pulmonary and feeding problems. There was no indication found by the clinicians involved for further investigations because pulmonary complaints were given priority over feeding disorders. Although drinking improved with age, eating of solid nutrition remained a problem. By age 5 years, the symptoms had gradually worsened. The patient developed a progressive failure to thrive (z scores; length –2.5; length to weight –1.5) and the patient started to vomit, especially solid foods. Furthermore, the patient presented with hematemesis and a microcytic anemia. Physical examination revealed no further abnormalities. Because a possible gastroesophageal reflux disease related to esophageal stenosis was suspected, an esophageal contrast study showed a distal esophageal stenosis. There was no focus on the stomach or the pylorus.
During a subsequent endoscopy, a mild reflux stenosis was found in the distal esophagus. Because the endoscope could pass this stenosis easily, no esophageal dilatation was performed. The gastric mucosa appeared to be inflamed and hemorrhagic. Furthermore, the stomach was rather distended and without peristalsis. Although a narrow lumen was observed, the endoscope could not pass the pylorus into the duodenum (Fig. 1). Finally, under radioscopy guidance an atraumatic guidewire was passed through the stenosis and a duodenal feeding tube was placed through the pylorus into the duodenum.
A consecutive abdominal ultrasound of the pylorus showed neither external compression nor any other pyloric structural abnormalities. To further investigate why the pediatric endoscope could not pass the duodenum (although esophageal contrast study described only a distal esophageal stenosis), diagnostic gastroduodenoscopy and laparoscopy were performed simultaneously. The tip of the endoscope was placed directly in front of the distal gastric stenosis. Via laparoscopy, transillumination of the light of the endoscope was located in the distal antrum just proximal to the pylorus (Fig. 2). There was neither external compression nor abnormality seen in the pylorus region. This observation caused strong suspicion for the existence of prepyloric web. Therefore, the laparoscopy was converted to a laparotomy with gastropylorotomy, and prepyloric web was found. This web almost completely obstructed the lumen of the distal antrum with a central opening of only 2 to 3 mm (Fig. 3). The web was partially resected and pyloroplasty was performed. Finally, a transanastomotic feeding tube was placed via the pylorus into the jejunum. Microscopic examination of the excised membrane showed hyperplastic mucosa and nonspecific active inflammation (Fig. 4).
Postoperatively the patient recovered well. The feeding tube was removed after 2 weeks and the patient resumed normal feeding. After 1 year, the patient still had minimal feeding problems, most likely because of the secondary atonic stomach.
This case report illustrates that symptoms of prepyloric web can be disguised by its consequences. In our patient, the prepyloric web was causing secondary gastroesophageal reflux with probable recurrent aspiration pneumonias (mainly in the right lobe). The medical focus was to search for a pulmonary cause of the pneumonia with a hypothesis of primary ciliary dyskinesia. Because of the misleading symptomatology and indistinguishable diagnostic results, the clinicians involved failed to consider a gastric outlet obstruction as a possible cause of the coughing and vomiting.
After years of more or less stability, at age 5 years the child's feeding problems deteriorated, with progressive esophageal passage problems in particular for solid food. In retrospect, liquid feeding and enteral tube feeding probably could still pass through the small aperture of the prepyloric web. However, when more solid food was later introduced, the symptoms of gastric outlet obstruction became progressive. At this point, secondary gastroesophageal reflux could have led to esophageal inflammation and the mild distal esophagus stenosis. This is probably the cause of the presentation of vomiting and hematemesis. There are other case reports that describe the onset of symptoms as a result of an acquired cause due to peptic diseases (2,3). However, prepyloric web is considered a congenital lesion that possibly results from failure of the antrum to recanalize after temporary occlusion by epithelium during embryogenesis (3).
The characteristics of a prepyloric web were already formulated in 1933 by Parsons and Barling as “the mucous membrane at the pyloric orifice passes inwards and forms a sort of diaphragm pierced by a small opening, but without any hypertrophy of the pyloric ring sphincter or pyloric canal” (4). The prepyloric web consists of 2 layers of mucosa. These layers may have a muscular component, usually perpendicular to the long axis of the antrum 1 to 2 cm proximal to the pylorus, and may have a central or eccentric aperture (5).
There are different diagnostic approaches known in the literature to diagnose prepyloric web. The traditional diagnostic study choice is the esophageal contrast barium study, with an accurate diagnosis of prepyloric web in 90% of the cases (9). The presence of a persistent, sharp, band-like filling defect in the antral region and the spraying of barium through a central or an eccentric aperture with a “jet effect” are the characteristic features for prepyloric web (3,9). It was misleading in our contrast study because it revealed a stenosis of the distal esophagus that in itself could explain the presenting symptoms. Also, in the literature there are descriptions of misleading contrast studies mimicking hypertrophic pyloric stenosis (2). A second diagnostic approach is ultrasound. Chew and coworkers (9,10) proposed 4 ultrasound diagnostic criteria of prepyloric web: demonstration of an echogenic diaphragm-like structure in the antral region, gastric dilatation, delay in gastric emptying, and a normal pylorus. In our case, an ultrasound was performed that showed a normal aspect of the pylorus. An esophageal contrast barium study or an ultrasound, both noninvasive procedures in young children, with a good chance of an accurate diagnosis, is the best diagnostic procedure when assessed by experienced staff. Another diagnostic technique described in the literature is endoscopy. This method can confirm the presence of prepyloric web and can be helpful in exploring other gastric pathologies (eg, peptic diseases, adhesions). Endoscopic diagnostic criteria for prepyloric web are a diaphragm with smooth mucosa and an opening of constant size and normal peristalsis distal to the web (11). Although the opening of the pylorus in the patient was small, the diagnosis of prepyloric web was not recognized. In the second combined approach of gastroduodenoscopy and laparoscopy, the diagnosis was easily confirmed. The usual treatment of prepyloric web, as performed in our patient, is surgical resection of the web. Although there are experiences of therapeutic upper gastrointestinal endoscopies in children, only Berr et al (12) described a successful endoscopic procedure in a child with a partially obstructive antral diaphragm, without the occurrence of restenosis.
In summary, this report illustrates that prepyloric web can present with a misleading and indistinct symptomatology. In hindsight, for this patient the recurrent airway infections caused by gastroesophageal reflux and eventually esophageal stenosis disguised the clinical symptoms of prepyloric web for years. The prolonged diagnostic approach could have been avoided if the clinicians initially had considered another origin of the symptomatology apart from the presumed ciliary abnormalities. The diagnostic approach described in this report, namely combined gastroduodenoscopy and laparoscopy, eventually provided the key insight into this anatomic problem.
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