Papilloma Formation in Esophagus after Covered Metal Stent Placement: Two Case Reports

Aims: To highlight an uncommon situation during stenting for obesity surgery complications. Place and Duration of Study: 1 st Propaideutic Surgical Unit, Hippokration Hospital, Athens between December 2008 and November 2010. Results: 2 cases of obese patients are presented where the placing of metal stents in esophagogastric region after leakage in the postoperative period of sleeve gastrectomy, resulted in formation of papilloma at the edge of these stents. Conclusion: May be these cases are two of the very few reports in the medical literature which describe mucosal hyperplasia in the esophagus at the edge of a covered metal stent placed for a benign condition.


INTRODUCTION
The authors present 2 cases of papilloma formation in esophagogastric region after placement of covered metal stent. The stents in both cases were initially placed after leakage in suture line, a complication after the bariatric operation sleeve gastrectomy. The stents were placed endoscopically and the papillomas were discovered after a period of 3 weeks. At this time the authors' intention was to withdraw the stents because the leakage was vanished in both patients.

Case 1
The first patient was an obese female 53 years old. The patient's body mass index (BMI) was 60 and her only medical comorbidity was increased blood pressure, for which she followed medication (disability class II in Global Burden of Disease). The patient underwent a sleeve gastrectomy laparoscopically. After 5 days of hospital stay a leak was identified with an upper GI series. No abscess or fluid collection was identified in her abdomen with further investigation. The authors proceeded to esophagogastroscopy and placed a covered metal stent at the proximal stomach, gastroesophageal junction extended upward to the esophagus. The post procedure period was uneventful and no leak was seen with barium contrast series. At the time the stent was discharged a mass protruded in the lumen of esophagus, incipient at the edge of the stent. Excisional biopsy was taken.

Case 2
The second case concerned a 31 years old female. She also was an obese patient (BMI: 46) and she had no medical history (disability class I in global burden of disease). The patient was also underwent a laparoscopic sleeve gastrectomy and she was discharged from hospital at the 5th postoperative day. The 10th postoperative day a readmission was taken place because the patient was presented with a severe abdominal pain and signs of peritonitis. After the resuscitation with fluids, electrolyte correction and treatment with antibiotics, her medical condition seemed to be improved and no operation was needed. CT scan showed fluid collection in the upper abdomen, which was diminished over time. The decision of a stent placement was taken and finally the covered metal stent was placed with endoscopy. After 3 weeks with no signs of leak the stent was taken off and at the endoscopy a papilloma was seen, protruded from the upper edge of the stent. A biopsy was also taken.
The mucosal hyperplasia was an incidental finding since it was not large enough to cause obstruction of the lumen. The biopsies of both cases revealed reactive mucosal hyperplasia with no signs of dysplasia or malignant degeneration. Human papilloma virus DNA by in situ hybridization and polymerase chain reaction was not detected in both of the patients.

DISCUSSION
Esophageal stenting is a common practice in situations like benign esophageal strictures, malignancy, tracheoesophageal fistula (Chen et al., 1998;Grund et al., 1998;Ramirez et al., 1997). After the onset of laparoscopic sleeve gastrectomy for treatment of morbidly obese patients, it was imperative the need for conservative treatment after major complications of this operation. Thus indications for esophagogastric stenting were expanded in situations which there are leakage in suture line especially in proximal stomach, near cardia notch (His insicura) (Eubanks et al., 2008) Covered metal stents are used in these situations to tamponade the site of leakage and allow oral feeding (Grund et al., 1998).
Complications after stent placement at the lower esophagus are migration of the stent, gastroesophageal reflux, bleeding and perforation (Cheng et al., 2004). In the case of malignancy it is quite common the tumor ingrowth within metal stent wires (Homann et al., 2008). It is also common in other sites, like ureterers and bile ducts, particularly in animal models the stent placement to cause extensive submucosal fibrosis and mucosal hyperplasia (Silvis et al., 1994;Thijssen et al., 1994). In esophageal metal stenting in human fibrosis, reactive hyperplasia and granulation tissue are rarely seen and these are reported to occur between the stent wires (Chen et al., 1998;Collina et al., 1980;Homann et al., 2008;Karras et al., 1999;Mayoral et al., 2000). Thus, the mucosal hyperplasia is an extremely rare condition at covered metal stents in esophagus, especially the appearance of protrusion from the edge of the stent like a pendiculated polyp as in the two cases the authors report.
Many investigators attribute the etiology of the phenomenon of mucosal hyperplasia in esophageal stent placement to mucosal injury. The mucosal injury is often the result of the handlings in order to put, expand and fixate the stent. Later the injury can result from the movements of the esophageal wall underneath the covered metal stent, which irritates and stimulates the mucosa sequentially. Maybe this is the stimulus for the mucosa to proceed to regeneration and hyperplasia (Wolfsen et al., 2004;Collina et al., 1980;Karras et al., 1999;Mosca et al., 2001). Nevertheless, the esophageal and gastric mucosa near the gastroesophageal region is not a mucosa amenable to immense regeneration and hyperplasia after local injury. More prominent are the infections of papilloma virus in this region and the subsequent development of a papilloma (Karras et al., 1999;Mayoral et al., 2000;Mosca et al., 2001). The role of the operation, because the patients are in the first postoperative days, is a phenomenon which cannot be estimated for the papilla formation. The fact that this operation is more frequently carried out and more experience in complications is obtained will allow us to study more the phenomenon of papilla formation during the metal stent placement.

CONCLUSION
May be these cases are two of the very few reports in the medical literature which describe mucosal hyperplasia in the esophagus at the edge of a covered metal stent placed for a benign condition.