Tophus: Difference between revisions

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Mikael Häggström (talk | contribs)
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==Preparation==
==Preparation==
A tophus specimen should be sent '''dry''' to the pathology department, and '''not''' be put in formalin.<ref group=notes>Formalin dissolves the crystals.</ref> A touch prep can be done initially, and at least if urate crystals remain suspected, the specimen is submitted in 100% alcohol for microscopy evaluation.
A tophus specimen should be sent '''dry''' to the pathology department, and '''not''' be put in formalin.<ref group=notes name=dissolves>Formalin dissolves the crystals.</ref> A touch prep can be done initially, and at least if urate crystals are not initially detected, the specimen is submitted in 100% alcohol for microscopy evaluation.<ref group=notes name=dissolves/>


==Microscopy evaluation==
==Microscopy evaluation==
Evaluation of a fresh tophus can start as a touch prep to look for needle-shaped crystals of urate. On polarized light, these will have negative birefriengence.
On a touch prep, look for needle-shaped crystals of urate. On polarized light, these will have negative birefriengence.
<gallery mode=packed>
<gallery mode=packed>
File:Light microscopy of a touch preparation of a gout tophus, showing urate crystals.jpg|thumb|Light microscopy of a touch preparation of a gout tophus, showing needle shaped crystals
File:Light microscopy of a touch preparation of a gout tophus, showing urate crystals.jpg|thumb|Light microscopy of a touch preparation of a gout tophus, showing needle shaped crystals