[Histonet] Amyloid by Congo Red

[Bryan Llewellyn]

This is a well known phenomenon of amyloid staining and it is fairly 
common. It is due to the fact that amyloid is a very variable material 
and different samples may react differently to the dyes. I suggest you 
restain using Highman's congo red method 
(http://stainsfile.info/StainsFile/stain/amyloid/congohighman.htm) is 
more reliable than Bennhold's. I always found it the more reliable. If 
it is still unstained, try a sirius red method (using CI 35780, sirius 
red F3B, NOT sirius red 4B). You might also want to consider thioflavine 
T and the other methods using dyes other than direct cotton dyes.

Read the article, which includes a list of methods, at: 
http://stainsfile.info/StainsFile/stain/amyloid/amyloid.htm

Bryan Llewellyn


Jeffrey Robinson wrote:
> Greetings to all Histotechs-  Here's an amyloid question for the braintrust.  We are cutting our slides and controls at 9 and staining in Congo Red for 1 hour.  The control stains fine but the patient tissue is staining negative even on cases that the pathologist assures us should be positive for amyloid.  We are using the Leica APEX charged slides with control and patient tissue on the same slide.  Does anyone have any thoughts on why the patient tissue is not staining?  Thanks!
>
> Jeff Robinson HT, HTL, Senior Histotechnologist, Sierra Pathology Lab, Clovis, CA.
>
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