Colon non tumor
Colitis (non-infectious)
Pill fragment associated colitis

Author: Raul S. Gonzalez, M.D. (see Authors page)

Revised: 6 May 2016, last major update May 2016

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Kayexalate colitis
Cite this page: Pill fragment associated colitis . website. Accessed June 24th, 2018.
Definition / general
  • Sodium polystyrene sulfonate (Kayexalate) is an ion exchange resin that binds intraluminal potassium; it can cause ischemia and intestinal necrosis, especially (but not only) if given with sorbitol (Am J Surg Pathol 1997;21:60)
  • Sevelamer, used to treat hyperphosphatemia in patients with chronic kidney disease, binds phosphate and has may cause injury to the gastrointestinal tract (Am J Surg Pathol 2013;37:1686)
  • Bile acid sequestrants (e.g., cholestyramine) may microscopically mimic other pill fragments but do not appear to cause injury (Am J Surg Pathol 2014;38:1530)
Essential features
  • Kayexalate causes mucosal injury, and sevelamer may also as well
  • Other pill fragments (such as bile acid sequestrants) can also be identified microscopically, but do not cause mucosal injury
  • Colon is most commonly involved gastrointestinal organ, but any can be affected
  • Resins can rarely be encountered outside the gastrointestinal tract (due to perforation, aspiration, etc.) (Diagn Pathol 2008;3:27)
  • Microscopic examination and clinical confirmation of medication use
Case reports
Clinical images

Images hosted on other servers:

Kayexalate induced colon ulcer
on colonoscopy

Microscopic (histologic) description
  • Kayexalate: bright purple crystals with fish scale appearance
  • Sevelamer: yellow/pink crystals; also fish scale appearance
  • Bile acid sequestrants: opaque orange polygonal/rhomboid crystals; usually NO fish scale appearance; may be spherical (Histopathology 2015;67:141)
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by: Dr. Raul Gonzalez, University of Rochester Medical Center, New York (USA)

Images hosted on other servers:

Kayexalate in colonic
ulcer (A) and along
lamina propria (B)

Incidental luminal polystyrene
sulphonate resin particles in
jejunal diverticular tissue

Particles at site of colonic
necrosis (Direct Schiff stain
with light counterstain)

Particles at site of aspiration
pneumonia (Ziehl-Neelsen stain
with light counterstain)

Positive stains
  • AFB: Kayexalate appears black, sevelamer appears magenta, and bile acid sequestrants appear dull yellow
Differential diagnosis
  • Dystrophic calcification can mimic Kayexalate but is a brighter purple
  • Bile can mimic sevelamer but has no pink coloration
Additional references