Hi,
During the sentinel node biopsy a radioactive tracer or blue dye is injected by your surgeon or doctor. This can be injected either around the tumor or underneath the nipple/ areola. Both techniques are used and both are very successful.
You could clarify this with your doctor , about what was injected and what procedure was done.
Let us know if you have any other doubts and post us about what your doctor tells you.
Regards.
My SNB was done like yours around the nipple. My lump was at the 1 o'clock position also, but was > 5cm. According to my doc, he said that the injection was to follow the path of the lymphatic drainage system from the nipple to the armpit. From there he would pinpoint where the injection landed in the first lymph nodes it found. I had 1 node positive.
Perhaps other SNBs were done differently because of their location in relation to another lymphatic flow, perhaps deeper in the tissue? Just guessing here.
At any rate, what course of treatment are you going to go through? I hope all goes well for you.