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Methods in pathology. The use of a colloidal silver (AgNOR) method in assessing bone marrow iron stores and
1Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison.
Abstract:
Previous observations indicated that a colloidal silver (AgNOR) method identifies iron-containing bone marrow cells. In this study we examined AgNOR-stained bone marrow smears from 30 selected patients and compared the results with the conventional Prussian blue (PB) method for staining storage iron and sideroblasts, including ringed sideroblasts (RS). Erythroid cells were easily identified, and iron granules stained as distinct, small, round, black dots. In all cases containing sideroblasts and RS, their proportion expressed as the percentage of all normoblasts was higher with AgNOR than with PB. Pronormoblastic and basophilic sideroblasts were detected more often with AgNOR than with PB. Sideroblasts were noted in cases with no PB-stainable iron. Ringed sideroblasts were identified in a number of cases in which they were nondetectable with PB. In cases of myelodysplastic syndrome, pronormoblastic and basophilic RS were found more often than with PB. Hemosiderin deposits within the macrophages were clearly visualized as black aggregates and were seen in cases with no PB-stainable iron. There were no instances where iron or any category of sideroblasts was seen with PB only. In our sampling, the AgNOR method was more sensitive yet specific, and it produced staining results of superior quality.
Insights
The colloidal silver (AgNOR) stain is a more sensitive method for detecting iron in bone marrow cells, including sideroblasts and ringed sideroblasts, compared to the Prussian blue stain. AgNOR identified iron in cases missed by Prussian blue, offering superior diagnostic potential.
Area of Science:
- Hematology
- Histopathology
- Biochemistry
Background:
- The Prussian blue (PB) stain is the standard for detecting iron in bone marrow.
- Previous studies suggested colloidal silver (AgNOR) staining could identify iron-containing cells.
Purpose of the Study:
- To compare the efficacy of the AgNOR stain with the conventional PB stain for identifying iron storage and sideroblasts in bone marrow smears.
- To evaluate the sensitivity and specificity of AgNOR for detecting sideroblasts, including ringed sideroblasts (RS).
Main Methods:
- AgNOR staining of bone marrow smears from 30 patients.
- Comparison of AgNOR results with conventional PB staining for storage iron and sideroblasts.
- Analysis of sideroblast proportions and detection of pronormoblastic and basophilic sideroblasts.
Main Results:
- AgNOR staining detected a higher proportion of sideroblasts and RS than PB staining.
- AgNOR identified sideroblasts and RS in cases where PB showed no stainable iron.
- Pronormoblastic and basophilic RS were more frequently detected with AgNOR, especially in myelodysplastic syndromes.
- Hemosiderin deposits were clearly visualized with AgNOR in macrophages, even when not detected by PB.
Conclusions:
- The AgNOR method is more sensitive and specific than PB for detecting bone marrow iron and sideroblasts.
- AgNOR provides superior quality staining and can identify iron-related abnormalities missed by PB.
- AgNOR shows promise for enhanced diagnosis in hematological conditions involving iron metabolism.