Kayexalate (sodium polystyrene sulfonate) aspiration.

The patient, a 63-year-old woman, had past medical history significant for diabetes mellitus, hypertension, congestive heart failure, and a pelvic mass. The serum electrolyte sample showed hyperkalemia (serum potassium 6.2 mEq/L, serum creatinine 4.1 mg/dL, blood urea nitrogen 87 mg/dL; the sample was not hemolyzed). She was taken to the emergency room. The hyperkalemia was treated with kayexalate (sodium polystyrene sulfonate) in the emergency room, and she was admitted to the hospital, where continued efforts were made to manage the hyperkalemia. However, she was found unresponsive the morning after admission, and efforts at resuscitation were unsuccessful. Postmortem examination revealed the pelvic mass to be a small cell neuroendocrine tumor, apparently arising from the cervix with extensive involvement of the uterine myometrium, extensive peritoneal implants, invasion into the wall of the bladder, compression of the ureters, and invasion of the inferior vena cava. There was no evidence of distant metastasis. She was also found to have massive cardiomegaly (dilated and hypertrophic) and nodular glomerulosclerosis. There was pulmonary congestion with edema. In addition, there were irregular, sharply angulated basophilic materials of varying sizes with little or no tissue reaction in the alveoli (Figure 1). These materials have parallel laminations (Figure 2). Degenerated bronchial cells are occasionally seen with the materials (Figure 2). These materials in the lungs are aspirated kayexalate (sodium polystyrene sulfonate). Kayexalate is a cation-exchange resin given enterally for the treatment of hyperkalemia. 1 There is characteristic basophilic, amorphous foreign material in airspaces on histologic sections. The identity of this material can be confirmed by Fourier transform infrared microspectrophotometry, 1 but this is often not necessary because of the characteristic appearance. The parallel laminations of the kayexalate are thought to be an artifact of sectioning. 2 Aspirated vegetable matter and meat fibers may be considered in the differential diagnosis, but these do not have the parallel laminations of kayexalate. Kayexalate aspiration typically does not cause pneumonia, but there have been reports of cases of pneumonitis following its aspi