Difference between revisions of "Tophus"
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==Microscopy evaluation== | ==Microscopy evaluation== | ||
On a touch prep, 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. | ||
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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: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: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> | 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> | ||
Revision as of 11:18, 12 November 2020
Author:
Mikael Häggström [note 1]
Contents
Preparation
A tophus specimen should be sent dry to the pathology department, and not be put in formalin.[notes 1]
Gross processing
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.
Light microscopy of a touch preparation of a gout tophus, showing needle-shaped crystals
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.[1]
In contrast, pseudogout (Calcium pyrophosphate dihydrate crystal deposition disease) displays rhombus-shaped crystals with negative birefringence.
Notes
- ↑ 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
- ↑ Bruce M Rothschild. Gout and Pseudogout Workup. Medscape. Updated: Jun 30, 2020
Image sources
