Among them, nine cases showed a cluster amplification in >90% of tumour cells population, whereas one case showed intra-tumour heterogeneity, having a different HER2 asset in different areas of the tumour: 33% of tumour cells had an average HER2 gene copy number of 4.5 and a HER2/CEP17 ratio of 2.4, whereas polysomy was present in 67% of nuclei with an average HER2 gene copy number of 3.6 and a HER2/CEP17 FISH ratio of 1.27. The gene discussed is ERBB2; the disease is neoplasm.