A 63-year-old man develops pain and swelling in his knee. It appears warm, red, and swollen with decreased range of movement. A diagnostic aspiration is performed. Which of the following will most likely distinguish pseudogout from gout?
Pseudogout (calcium pyrophosphate crystals - CPPD) is distinguishable from gout by positive birefringent crystals. CPPD are short, blunt rhomboids, and urate crystals (seen in gout) are needle-shaped with negative birefringence.
positive birefringent crystals
acute onset
involvement of single joints
involvement of large joints
Immunology and Rheumatology