ERBB2 and neoplasm: Table 5 shows the comparison between HER2 protein expression evaluated on histological sections of 39 primary tumours and paired metastatic sites. Overall concordance was 94.9%. Of the 39 matched cases the single discordant case was that also showing discordant FISH results. In this case, HER2 immunostaining was negative in the primary tumour (Figure 1B), whereas it showed a strong basolateral staining in 15% of cells in the metastasis (Figure 2B).