Even though all IBC patients were HER2-positive via IHC or FISH (S1 Table), only 16 of 20 tumours were called as having ERBB2 amplification; two tumours (IBC011 and IBC029) harboured gains and two tumours (IBC007 and IBC028) had neither amplification nor gain of ERBB2 (Fig 2B). Here, ERBB2 is linked to inflammatory breast carcinoma.