My sister has a very hard lump underneath her arm. It is growing and her doctor says that it has blood flow to it, that it is not a lymph node or a clogged gland. She has had a mamogram, and an ultrasound but the doctor still does not know what this lump is. Her doctor is planning on removing the lump in her office as the lump is "close to the skin" and sending it in for a biopsy. Please what is your opinion on what this lump may be and is my sisters' doctor pursuing a wise course of action?

Optional Information:
Female , Age: 45

Already Tried:
details are my sisters and what shes tried has already been answered