Abstract
Objective: Although polarizing microscopes are commonly used for the diagnosis of pseudogout, they are very expensive and not always available in small hospitals. We investigated visualizing calcium pyrophosphate dehydrate (CPPD) crystals using Gram stain, and investigated the usefulness of this technique for the diagnosis of pseudogout.
Methods: Twenty patients with suspected monoarthritis were investigated in our hospital. Aspirated joint fluids were assessed with both a polarizing microscope and Gram stain. Patients were diagnosed as pseudogout in the presence of CPPD crystals confirmed via a polarizing microscope. We visualized the joint fluid via Gram stain to detect crystals and bacteria. We estimated the sensitivity and specificity of the Gram stain for the diagnosis of pseudogout.
Results: Twelve patients were diagnosed as pseudogout, two patients had gout, two patients had septic arthritis, and four patients had other diseases. Using the polarizing microscope, 12 patients were CPPD-positive, and eight patients were CPPD-negative. Using Gram stain, 11 patients were crystal-positive, and nine patients were crystal-negative. The sensitivity and the specificity of Gram stain for the diagnosis of pseudogout was 92% and 100%, respectively.
Conclusion: Gram stain may be useful in the diagnosis of pseudogout.
