To the Editor.—
Over the past several years, I have noted that decalcified marrow fails to react with Prussian blue stain for iron. The phenomenon does not seem to be mentioned in the literature.This was first noted in examining bone-marrow needle biopsies and clot sections in staging Hodgkin disease. The decalcified needle biopsy specimens showed about 50% reduction in hemosiderin compared to the clot sections, and often when the latter showed normal amounts of iron the decalcified material would have none. The agent we use for decalcification (manufactured by DuPage Kinetic Laboratories, Inc., Downers Grove, Ill) is rapid and therefore very popular, but must also remove iron. This could obviously lead to false-negative results. One simple way to obviate this problem, if only a biopsy core specimen is available, is to first make several "touch" preparations from the marrow biopsy specimen and submit one of these for iron stain.