If the diagnostic mammogram and ultrasound studies indicate a biopsy is necessary, tissue will be removed from the breast and sent to a lab where a pathologist will examine the tissue for cancer cells.

There are three common types of biopsies:

• Fine-Needle Aspiration
  This procedure takes just a few minutes. It is most often performed if a lump appears to be a cyst. If the lump is filled with fluid, the fluid is removed from the lump using a thin needle and a syringe. Removing the fluid from a cyst will make the cyst go away, but it may recur. Most often, the fluid is only sent for testing if it is bloody or if there are other reasons the doctor is concerned. 
• Core Needle Biopsy
  A needle with a special cutting edge is inserted through a small incision in your skin and small core samples are taken.
  
  Ultrasound may be used as a guide during the biopsy. Ultrasound-guided needle biopsy is most often used when lumps are hard to feel on a breast exam or see on a mammogram.
  
  During a stereotactic core needle biopsy, a three-dimensional x-ray is used to guide the biopsy needle into the appropriate location.
• Surgical Biopsy
  Biopsies may be performed as an operation and during the procedure all or most of the breast lump is removed. Sometimes a wire is placed before the operation to guide the surgeon to a suspicious abnormality on mammography or ultrasound that cannot be felt. The radiologist places the needle into the breast so that the tip of the needle is in the area of breast change. Then a fine wire is placed through the needle. The needle may be removed while the wire remains in place. During the surgery, the surgeon uses the tip of the wire as a guide to what tissue needs to be removed.