Ischemic colitis with mucosal injury and a pseudomembrane. Note the presence of rhomboid-shaped crystals in the inflammatory debris. Image

A close look at those rhomboid crystals.

Extensive inflammatory exudate admixed with triangular and rhomboidal non-polarizing crystals adherent to the epithelium. Kayexalate may cause an ischemic pattern of mucosal damage often associated with an inflammatory exudate.