Special Techniques Applicable to Bone Marrow Diagnosis

A Perls’ or Prussian blue stain (Figs 2.1 and 2.2) demonstrates haemosiderin in bone marrow macrophages and within erythroblasts. Consequently, it allows assessment of both the amount of iron in reticulo-endothelial stores and the availability of iron to developing erythroblasts. Assessment of storage iron requires that an adequate number of fragments are obtained. A bone marrow film or squash will contain both intracellular and extracellular iron, the latter being derived from crushed macrophages. It is usual to base assessment of iron stores mainly on intracellular iron since iron stains are prone to artefactual deposits and it can be difficult to distinguish between extracellular iron and artefact. Iron stores may be assessed as normal, decreased or increased, or may be graded as 1+ to 6+ as shown in Table 2.1, grades of 1+ to 3+ being considered normal. Alternatively, iron stores may be graded as 1+ to 4+ [3,4]. Examination of a Perls’ stain of a bone marrow film allows adequate assessment of erythroblast iron as long as a thinly spread area of the film is examined with optimal illumination. A proportion of normal erythroblasts have a few (one to five) fine iron-containing granules randomly distributed in TWO