[Histonet] Pigment in H&E slides

[Joanne Clark]

Hi Histonetters, I was hoping you all could help me identify a strange pigment I have occassionally seen in my H&E slides.  It's not a formalin pigment and looks to be in the tissue, but on top at the same time.  When you focus up and down on it with the microscope its slightly refractive.  It looks more to me like a precipitate really than a pigment.  It doesn't happen on all slides just on the odd one which makes it easier to rule out formalin pigment.  IF the pH was off on my formalin, all the blocks would have pigment in them.  It almost looks to me like talcum powder.  I was able to remove it by bleaching it out with potassium permanganate.  Any ideas?