Difference between revisions of "Tophus"

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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.
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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>
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==Gross processing==
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[[File:Gross pathology of tophus.jpg|thumb|A large tophus.]]
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Preferably make a touch prep for polarized light microscopy. At least if urate crystals are not initially detected, take sections to be put in 100% alcohol and tell the histology lab to prepare it as per gout protocol.<ref group=notes name=dissolves/> With characteristic crystals on a touch prep, sections may possibly be submitted in formalin.<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.
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On a touch prep, look for needle-shaped crystals of urate. On polarized light, these will have negative birefriengence.
<gallery mode=packed>
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<gallery mode=packed heights=180>
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
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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:Uric acid crystals in polarized light.png|Uric acid crystals in polarized light, showing negative birefringence, with yellow color when aligned parallel to the axis of the red compensator, and blue when aligned perpendicularly to it.<ref>{{cite web|url=https://emedicine.medscape.com/article/329958-workup|title=Gout and Pseudogout Workup|author=Bruce M Rothschild|website=Medscape}} Updated: Jun 30, 2020</ref>
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File:Birefringence microscopy of gout, annotated.jpg|Uric acid crystals in polarized light, showing negative birefringence, with yellow color when aligned parallel to the axis of the red compensator, and blue when aligned perpendicularly to it.<ref>{{cite web|url=https://emedicine.medscape.com/article/329958-workup|title=Gout and Pseudogout Workup|author=Bruce M Rothschild|website=Medscape}} Updated: Jun 30, 2020</ref>
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File:Birefringence microscopy of pseudogout, annotated.jpg|In contrast, '''pseudogout''' (Calcium pyrophosphate dihydrate crystal deposition disease) displays rhombus-shaped crystals with negative birefringence.
 
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Revision as of 11:18, 12 November 2020

Author: Mikael Häggström [note 1]

Preparation

A tophus specimen should be sent dry to the pathology department, and not be put in formalin.[notes 1]

Gross processing

A large tophus.

Preferably make a touch prep for polarized light microscopy. At least if urate crystals are not initially detected, take sections to be put in 100% alcohol and tell the histology lab to prepare it as per gout protocol.[notes 1] With characteristic crystals on a touch prep, sections may possibly be submitted in formalin.[notes 1]

Microscopy evaluation

On a touch prep, look for needle-shaped crystals of urate. On polarized light, these will have negative birefriengence.

Notes

  1. 1.0 1.1 1.2 Formalin dissolves the crystals.
  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

Main page

References

  1. Bruce M Rothschild. Gout and Pseudogout Workup. Medscape. Updated: Jun 30, 2020

Image sources