Bottom line: AVOID FORMALIN and WATER
When examining peri-articular tissues, always be mindful of possible crystal deposition disease – namely gout (uric acid) or pseudogout (calcium pyrophosphate).
Crystals may appear white or tan and chalky or crumbly.
If the tissue has gross suspicion for crystals (or the patient has a history of gout) – DO NOT LET THE TISSUE TOUCH FORMALIN!
Uric acid crystals are water soluble and are destroyed in routine formalin processing. They require alcohol fixation and anhydrous processing for microscopic visualization.
Pseudogout crystals are not destroyed, but gross differentiation between the two may not be possible.
- Fix the tissue in alcohol.
- Do NOT place cassettes on the normal racks for histology pickup.
- Instead, call Ryan or the Histo lab for special alcohol processing.
- Call your attending with questions.