Inflammatory Pseudotumor Containing Kayexalate Crystals

Abstract

Kayexalate (sodium polystyrene sulfonate), a cation exchange resin often used to treat hyperkalemia, is known to produce gastrointestinal complications in a minority of patients. These complications range from mild gastrointestinal bleeding to perforation with acute abdomen. The typical histopathologic findings include mucosal ulceration, necrosis, and the presence of polygonal basophilic refractile crystals with a "fish scale" appearance. We present a unique case of Kayexalate crystals embedded in a perihepatic inflammatory pseudotumor, developing adjacent to a colostomy site in a 62-year-old woman following Kayexalate treatment. Microscopically, the lesion demonstrated a myofibroblastic proliferation rich in histiocytes and inflammation (lymphocytes, plasma cells, and eosinophils) as well as the presence of scattered typical Kayexalate crystals. This is the first report of extraintestinal Kayexalate identification in association with an inflammatory pseudotumor.

Resin-Induced ColonicPseudotumor: Rare Complication from Chronic Use of Potassium Binders in a Hemodialysis Patient

“…The crystals end up internalizing within the mucosa or embedded within a pseudotumor composed of dense inflammatory cells, giving the aspect of a luminal mass. Consistent with this possibility, a case report described polystyrene sulfonate embedded in a perihepatic inflammatory pseudotumor adjacent to a colostomy site [ 9 ]. It has also been demonstrated that simple inoculation of any tissue with sodium polystyrene sulfonate leads to an acute inflammatory reaction within 24 hours [ 8 ].…”

“…The existing literature does describe only one case where the patient developed a gastrointestinal complication after a prolonged use of sodium polystyrene sulfonate. The importance of identifying the sodium polystyrene sulfonate crystals in these situations is evident in order to avoid unnecessary investigations, and possibly deleterious interventions [ 9 ]. Here, we report a mistaken diagnosis that could have resulted in unnecessary subtotal colectomy for a cecal mass.…”

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

“…SPS-induced colonic pseudotumors have been described. In all cases, the biopsies were negative for dysplasia with only SPS crystals and inflammation identified [4,5,15].…”

Lower Gastrointestinal Bleeding Associated With Sodium Polystyrene Sulfonate Use

“…The hallmark of SPS toxicity is the identification of kayexalate crystals, visible with standard hematoxylin and eosin staining and showing characteristic polygonal, refractile, basophilic appearance and typical fish scale/mosaic pattern, which displays red color on periodic acid-Schiff and acid-fast stains. 9 …”