This image is an H&E stained section. The tumor area in an H&E slide is marked for subsequent IHC and FISH testing.
It is critical that analysis be conducted on the invasive component of the breast cancer. This is because HER2 is, for unclear reasons, frequently increased (overexpressed and/or over amplified) in ductal carcinoma in situ (DCIS), and the clinical implications of this finding are uncertain.