Esophageal Pseudotumor Secondary to Treatment with a Potassium Binder Resin: A Case of Severe Esophagitis Mimicking a Malignancy

Background. Sodium polystyrene sulfonate is a resin used to treat hyperkalemia. Colonic mucosal injury, intestinal ischemia, necrosis, and perforation have been widely reported in the literature, but few cases have reported upper gastrointestinal injury and identify the endoscopic features. Case Presentation. We describe a case of an 83-year-old male, with no prior esophageal symptoms, who developed dysphagia after being treated with sodium polystyrene sulfonate for hyperkalemia. Endoscopic features consistent with severe esophagitis and a mass in the lower esophagus mimicking a malignancy were found, and pathology confirmed resin-induced esophagitis. Discussion. The identification of basophilic crystals in the epithelium with surrounding inflammation is a hallmark of sodium polystyrene sulfonate-induced mucosal injury. Several direct and indirect mechanisms by which SPS may cause mucosal injury have been identified. Prolonged stasis of crystals in the lumen has the potential of developing erosions and ultimately necrosis. The internalization of these crystals to the underlying intestinal mucosa with the combination of the inflammatory response may give an appearance of a luminal mass that can mimic a malignancy. Recognizing the wide-ranging endoscopic findings of resin-induced mucosal injury in the esophagus is fundamental to consider a potential side effect of sodium polystyrene sulfonate. The use of this resin should be avoided in patients with suspected esophageal motility disorder.