Challenges in Diagnosing Medication Resins in Surgical Pathology Specimens: A Crystal-Clear Review Guide

- Medication resins, including Kayexalate, sevelamer, and bile acid sequestrants, can be encountered in gastrointestinal tract specimens. Their classic histologic appearances have been well documented, but pathologist recognition of the resins is 75%, patient history is not always available, and atypical morphologic findings are sometimes present.

- To offer a succinct overview of resins in the gastrointestinal tract, including typical and atypical appearances, in order to serve as a quick reference guide.

- The study comprises published literature, survey data, and our personal experiences.

- Classic morphology is the benchmark for identifying these resins, but color, location, and fish scale pattern can deviate from the norm, making proper identification a challenge. Patient history should be sought whenever possible, and ancillary staining is an option when necessary. Additionally, the presence of resins should prompt the pathologist to search for potentially related diagnoses (namely, causes of diarrhea in patients on bile acid sequestrants and diagnoses associated with renal failure in patients on Kayexalate or sevelamer).