Last updated: October 17, 2014
CPT Code: Crystal identification by light microscopy 89060
Description: Crystals of cholesterol are occasionally found in joints, bursae, tendons, pericardial and pleural fluid, and skin. Two morphologic forms occur: highly birefringent, large, flat, rectangular plates with notched corners (80–100 f.Lm) and needle-shaped, strongly birefringent crystals (2–20 f.Lm). The former are more common and appear as “stacked panes of glass.”
Method: Crystals are best identified by polarized light microscopy but may be seen with ordinary light microscopy.
Found in: Cholesterol crystals are often found in the synovial fluid of patients with RA, SLE, osteoarthritis, hyperlipidemia, and chronic tophaceous gout. They are also found in xanthomas, cholesterol tophi, calcinosis cutis, rheumatoid nodules, and pleural and pericardial effusions owing to RA, tuberculosis, or malignancy. They may be found in atheromatous plaques and in cholesterol emboli. Cholesterol crystals can activate the NLRP3 inflammasome and thus their contribution to inflammation related to atherosclerotic disease is under investigation.
Indications: Crystals are usually an incidental finding, and testing is rarely requested.