I have used Penfix  for years with great results, especially in these days of 
getting breast biopsies out as "rush" cases. i know that you are to use it 
after the gross is done and that the cassettes are to be placed in the 
fixative. No tissue is to be stored in Penfix. Since it is 
alcoholic-formalin, i see no problem with IHC but one of our Pathologist in 
the region is questioning it as how it relates to IHC's. This is the first 
time that i have heard the fixative questioned. Since using the Penfix as  
one of the solutions on the processor, we seldom , if ever, have unfixed 
breast tissue.
marilyn