Validation of an automated iron stain process for use with bone marrow aspirate smear slides

The assessment of bone marrow iron stores is typically performed on an aspirate smear slide that has been manually stained by a technologist using a commercially available kit. This approach can contribute to inconsistent results and limit the broad use of iron staining in bone marrow specimens, particularly when laboratories have low staffing and/or high specimen volumes. Here, we describe the adaptation and validation of the Ventana Benchmark automated stainer and iron stain kit for routine clinical use of staining iron in bone marrow aspirate smear slides. We assessed accuracy and precision of the Ventana automated iron staining protocol compared to the Perls Prussian blue manual iron staining index method. Hematopathologists assigned Gale scores and enumerated the percentages of erythroid sideroblasts on paired patient bone marrow aspirate smear slides stained by the automated method and the manual iron staining method. We found a similar level of performance of the Ventana automated iron stain relative to the index manual method (as assessed by Pearson correlation and Bland-Altman analyses). In addition, there was low imprecision between replicates performed via the automated iron stain protocol. We also report superior qualitative findings of the automated method in ease of localization of iron storage, visualization of sideroblasts, and counterstain consistency. Automated iron staining of bone marrow aspirate smear slides performed similarly to the manual method and may allow for accurate routine evaluation of bone marrow iron stores as part of bone marrow analysis.