Fig. 4From: Articular and periarticular spinal calcifications in relation to synovial fluid findings in patients with calcium pyrophosphate dihydrate deposition disease (CPPD)CPPD crystals by polarized microscopy. Rhomboid-shaped positively birefringent crystal (blue when oriented parallel to the axis of the compensator (blue arrow) and yellow when perpendicular to the axis of the compensator (yellow arrow)) (magnification × 40)Back to article page