Calcium polystyrene sulfonate-induced colitis: advanced characterization of crystal nature with infrared spectroscopy.

Classical potassium binders are used in the treatment of hyperkalemia and are widely associated with gastrointestinal side effects, with crystal colonic injury being rare but potentially fatal. In this report, we describe the case of an 82-year-old male with hyperkalemia and calcium polystyrene sulfonate crystal-associated colonic necrosis. Traditionally, this diagnosis has relied on the examination of crystal morphology and polarization through microscopy.

Anal canal gastrointestinal stromal tumors: case report and literature review.

Gastrointestinal stromal tumors (GIST) are an uncommon group of tumors of mesenchymal origin. GIST of the anal canal is extremely rare. At present, only 10 cases of c-kit positive anal GIST have been reported in the literature.