[Histonet] GMS Question

[Goins, Tresa]

To get a positive PAS or GMS fungal stain, one must oxidize the carbohydrate in the fungal cell wall.  
Chromic acid is a stronger oxidizer than periodic acid, so would work better with mature fungal cell walls that are highly polymerized.
Treat an immature cell wall for too long, and you may get a false negative because the carbohydrate structure no longer resembles a fungal cell wall.

Tresa

-----Original Message-----
From: Paula Lucas [mailto:plucas at biopath.org] 
Sent: Friday, May 01, 2015 8:17 AM
To: histonet at lists.utsouthwestern.edu
Subject: [Histonet] GMS Question

Hello,

 

I think I already know the answer but I'm not sure why so if someone can help me understand the theory behind it, I would greatly appreciate it.

 

Currently, we use the Richard Allen kit for the GMS stain and it uses Periodic Acid as the 1st step.  

We use a control tissue from a case we had that was positive for fungus and it's a fungus ball from the Rt Maxillary. 

We ran a test for fungus on a different and current case of the same tissue (different patient): Rt Maxillary sinus.

 

The control tissue did work, but the patient's tissue did not, so the doctor ordered a PAS for fungus and this clearly showed the fungal elements nicely.


 

My question is why would the control and patient tissue have different results when they are both fungus balls from the same specimen source?

 

Thanks in advance,

Paula

Lab Manager

Bio-Path Medical Group

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