title: Inflammatory Pseudotumor Containing Kayexalate Crystals: A Case Report and Review of the Literature.
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.
authors.affiliation: Mayo Clinic, Rochester, MN, USA romano.ryan@mayo.edu.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Romano
authors.affiliation: Ameripath, Lubbock, TX, USA.
authors.forename: Seshadri
authors.initials: S
authors.lastname: Thirumala
authors.affiliation: Lubbock Diagnostic Radiology, Covenant Health System, Lubbock, TX, USA.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Cushman
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Taofic
authors.initials: T
authors.lastname: Mounajjed
mesh_terms: D002411:Cation Exchange Resins / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006104:Granuloma, Plasma Cell / Q000139:chemically induced / Q000473:pathology*; D006801:Humans; D006947:Hyperkalemia / Q000188:drug therapy*; D008875:Middle Aged; D011137:Polystyrenes / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D002411:Cation Exchange Resins; D011137:Polystyrenes; C003321:polystyrene sulfonic acid
keywords: Kayexalate; inflammatory pseudotumor; myofibroblastic; perihepatic pseudotumor; pseudotumor