American Society for Clinical Pathology (ASCP) Histotechnologist Practice Test

What does Prussian blue stain specifically detect in tissue samples?

1. Calcium deposits

2. Ferric iron

3. Collagen fibers

4. Lipid accumulation

The correct answer is: Ferric iron

The Prussian blue stain is specifically designed to detect ferric iron (Fe³⁺) in tissue samples. It is a histological technique that utilizes the reaction between ferric iron and potassium ferricyanide, resulting in a characteristic blue coloration in areas where ferric iron is present. This staining method is particularly useful in identifying hemosiderin, a storage form of iron that can accumulate in conditions of iron overload or hemorrhage. In histopathological contexts, recognizing the presence of ferric iron can help diagnose various conditions, such as hemochromatosis or hemosiderosis, as these conditions are associated with excess iron deposition in tissues. The blue color formed is quite distinct and easily visualized under a microscope, making Prussian blue a valuable tool for pathologists in their evaluative processes. Other staining methods are used for different tissue components; for example, calcium deposits might be detected using von Kossa or Alizarin Red stains, while collagen fibers are typically assessed with Masson's trichrome stain. Lipid accumulation can be identified using Sudan stains or oil red O. Each of these stains targets specific constituents within the tissue, further highlighting the specificity of Prussian blue for ferric iron.