The effect of decalcifying solutions on hemosiderin staining

To determine whether routine decalcification may reduce the amount of stainable iron that is visible on tissue sections, samples of liver and lung tissue with excessive iron stores were placed in three standard decalcifying solutions (i) formic acid [33%], formaldehyde [4%], and NaCl [0.85%]; (ii) formic acid [30%], formaldehyde [4%], and water; and (iii) nitric acid [5%] for 24, 48, 72, and 96 h. After exposure to the decalcifying solutions, the tissues were stained with Perls stain. The slides were examined blind and the intensity of iron staining was scored semiquantitatively from 0 to 3+. The trend in all samples over the course of the experiment (96 h) was for reduction in the intensity of hemosiderin staining. As the amount of stainable hemosiderin in tissues may be significantly altered by decalcification, the absence of hemosiderin in tissues adjacent to a fracture site does not necessarily indicate that the injury was acute.