What are these crystals that were aspirated from the bursa of an elbow of a patient with rheumatoid arthritis?
Answer A. CholesterolThe rectangular, platelike crystals with strong birefringence (both positive and negative) and notched corners are characteristic of cholesterol crystals. Cholesterol crystals are occasionally seen in the bursal fluid of patients who have rheumatoid arthritis.
Cholesterol
Calcium apatite
Calcium oxalate
Calcium pyrophosphate dihydrate
Immunology and Rheumatology