Immunocytochemical staining for the c-erbB-2 gene product in breast aspirates: a preliminary report.

The results of the determination of c-erbB-2 gene expression by immunocytochemical staining of cytological aspirates, prepared by cytocentrifugation, have been compared with paraffin-embedded tissue sections from the same tumour. Our results show equivalent staining in 20/22 cases, with six cases being both scored positive and fourteen cases being both negative. Two samples gave conflicting results. One case was scored as being positive on the cytological aspirate, whereas in the tissue sections taken from the same tumour positive staining was only seen in areas of non-invasive intraduct carcinoma. This sample was scored as being negative. In another case, cytoplasmic staining with less than 50% of the cells showing any positivity was observed in the cytospin sample, with negative staining in the corresponding tissue section. We conclude that expression of c-erbB-2 immunostaining is detectable on cytological preparations prepared by cytocentrifugation but must be interpreted with caution in tumours which may have a large intraduct component or which give predominant cytoplasmic staining.