Iron staining on bone marrow aspirate smears is commonly part of the standard order protocol for bone marrows aspirates. The iron staining procedure utilizes the Prussian Blue stain for ferric iron to assess bone marrow iron stores. This procedure is particularly helpful when evaluating patients with anemia, iron overload, myelodysplasia, etc. In the adult setting, it is commonly performed on the bone marrow biopsy, but can be requested on the aspirates as well.
In the pediatric setting, it is less likely to be part of the standard order set since young children rarely have stainable iron stores. However, iron staining may be requested on patients with congenital anemia and possible mitochondrial defects to look for sideroblastic anemia.
In this technique, iron will stain blue and will normally be found in bone marrow stromal/ macrophages, which are found in the spicules. On aspirate smears, without fragments/spicules, it is not possible to evaluate for iron stores. However, if there are nucleated red blood cells (NRBCs) present, it is still possible to look for the ringed sideroblasts, common in sideroblastic anemias.
The image on the right is a field from a bone marrow slide from a patient with congenital sideroblastic anemia. The NRBC indicated by the red arrow is a normal siderocyte with few granules of hemosiderin scattered through the cytoplasm. The NRBC that is indicated by the blue arrow has a large number of hemosiderin granules concentrated in the mitochondria that surround the nucleus. This is a pathologic ringed sideroblast.