Gout : Alcohol-fixed tissues
Uric acid crystals are water soluble and require alcohol fixation and anhydrous processing for optimal visualization. In alcohol-fixed tissues (shown here), they appear as bundles of brown needle-like structures that are negatively birefringent under polarized light. Dystrophic calcification can develop in some cases. When there is superimposed infection, neutrophils dominate the inflammatory response. Image courtesy of: Jian-Hua Qiao, MD, FCAP, Los Angeles, CA, USA.