Influence of fixation and preparation on the AgNOR distribution in routinely processed breast cancer specimens

AgNOR staining is mostly performed on unstained sections from paraffin-embedded material. This well-established application may be limited, if only a small biopsy or cytologic material is available. In this study, we analyzed the influence of different routine preparation types from histology and cytology on AgNOR staining results. 15 cases of ductal breast carcinoma were investigated using five different preparations per case: frozen sections, sections from formalin-fixed and paraffin-embedded, previously frozen material, sections from routinely formalin-fixed and paraffin-embedded fresh material, alcohol-fixed and air-dried cytological smears. After application of a modified combined Feulgen-AgNOR staining technique, AgNOR quantification on 150 nuclei per specimen was performed by TV-image analysis. For each preparation type adequate AgNOR staining results were obtained. Although there were a number of statistically significant correlations, the median values for the mean nuclear area, the mean number of AgNORs per cell, the mean AgNOR area per cell and the mean AgNOR sum area per cell were quite different within the 5 preparation types. This means that results, obtained with one preparation type, may not be taken as standard for a different one.