Noreen S. Gilman, HT (ASCP) CLS, Supervisor of Histopathology at Broward 
General Medical Center in Ft. Lauderdale FL asks

>>Once again I find myself asking for special stain help from my fellow 
histonetters. This concerns the GMS stain. One of my techs tells me that a 
friend of hers from another hospital is using Periodic Acid instead of 
Chromic acid, and that there is a written procedure for it. I must admit that 
I have been out of the technical area for several years, and I had never 
heard of this. They are going to fax me a copy, but I thought I'd get some 
feedback from you guys first.<<

In the last few years many commercial suppliers of GMS reagents have quietly 
substituted periodic acid for chromic acid. The chromic acid technique is 
necessary to demonstrate fungal cell walls, particularly in Histoplasma, and 
periodic acid is not a sufficiently strong oxidant to accomplish this. Most 
labs I do locum tenens work in don't even realize this change has occurred.

Chromic acid is a strong oxidant and a sufficient environmental hazard that 
people understandably want to be rid of it. Nonetheless, Good Marketing and 
Good Management do not replace scientific evidence that periodic acid 
oxidation is sufficient. If there's any reliable literature on this subject, 
somebody please cite it!

Bob Richmond
Samurai Pathologist
Knoxville TN