Examination of joint fluid diagnostic staining method for hydroxyapatite deposition disease

Abstract

Crystal-induced arthritis arises from variety of crystal formations, with gout (sodium urate crystals) and pseudogout (calcium pyrophosphate crystals) being the most common forms of crystal-induced arthritis in rheumatic diseases, although hydroxyapatite (HA) crystals are a rare contributor to this condition. HA crystals, lacking characteristic birefringence under a simple polarizing microscope, pose challenges in accurate assessment. Electron microscopy or Alizarin Red S staining is conventionally employed for identification; however, accessibility to these methods is limited in many healthcare institutions. In this study, Von Kossa’s method, Hematoxylin-Eosin stain (HE) and Giemsa stain were investigated as the most useful staining techniques for the diagnosis of hydroxyapatite deposition in joint fluid. Results indicated positive staining for HA crystals in all four methods, with Von Kossa’s method and HE stain exhibiting notably high positivity rates. Image analysis, utilizing RGB histogram, revealed that Von Kossa’s method offered distinct contrast among HA crystals, leukocytes, and the background. The findings suggest that Von Kossa’s method holds promise as a viable alternative to Alizarin Red S staining for the identification of HA crystals. This underscores its potential utility as a practical diagnostic tool for crystal-induced arthritis in scenarios where conventional methods are unavailable.