[Histonet] Re: gout processing procedure

[Bob Richmond]

Gouty tissue - containing monosodium urate crystals - should be fixed
in absolute alcohol, and processed into xylene and paraffin directly -
a rather cumbersome thing to do.

Urate crystals, particularly in large deposits (tophi), often survive
formalin fixation and routine processing anyway.

If any crystalline material is seen on gross examination, it's better
to pick it out with a needle, suspend it in a drop of water or
alcohol, and look at with a polarizing system that includes a full
wave plate (the pee lab microscope usually has one of these, the
pathologist usuallly doesn't). If you see the characteristic
negatively birefringent crystal needles with this approach, you don't
need to do anything else.

Bob Richmond
Samurai Pathologist
Knoxville TN