A 60-year-old male with a history of chronic kidney disease presents with severe hyperkalemia. He was treated with an oral resin to lower his potassium levels. A few days later, he developed abdominal pain, and a biopsy of his colon revealed basophilic crystals with a "fish scale" appearance under H&E staining. Special stains show black crystals with AFB and hot pink coloration with PAS-D.

A 70-year-old male with coronary artery disease and elevated cholesterol levels presents with new-onset constipation and abdominal discomfort. He has been taking a medication that binds bile acids. A biopsy of his colon reveals orange-black amorphous crystals under H&E staining, but no fish scales are observed.

A 52-year-old dialysis patient with chronic kidney disease is on a phosphate binder and presents with gastrointestinal discomfort. A biopsy shows broad, curved crystals with a double-toned appearance under H&E, magenta crystals with AFB staining, and lavender crystals with PAS-D.