If the follow up imaging still does eliminate the abnormality you will be scheduled for a biopsy. There are several different types of biopsies that are designed to look at specific types of abnormalities.  A fine needle aspiration is used to diagnose a breast lump while stereotactic biopsies zone in areas of micro-calcifications.

The types of breast biopsies include:

• Fine needle aspiration (FNA): Fine needle aspiration is a non-surgical form of breast biopsy in which a small needle is used to withdraw a sample of cells from the breast lump. If the lump is a cyst (fluid-filled sac), removal of the fluid will cause the cyst to collapse. If the lump is solid, cells can be smeared onto slides for examination.
• Core biopsy: Similar to FNA, but a core biopsy uses a larger needle because actual breast tissue is removed, rather than a tiny sampling of cells. A sample of the lump is removed, but not the entire lump. The types of core biopsies include ultrasound-guided core biopsy and stereotactic biopsy.
• Ultrasound-guided core biopsy: This technique obtains breast tissue without surgery. A biopsy needle is placed into the breast tissue. Ultrasound helps confirm correct needle placement -- using sound waves reflected off breast tissue -- so the exact location of the abnormality is biopsied. Ultrasound can distinguish many benign lesions, such as fluid-filled cysts, from solid lesions. Tissue samples are then taken through the needle.
• Stereotactic biopsy: Stereotactic biopsy involves centering the area to be tested in the window of a specially designed instrument. Mammogram films called SCOUT films are taken so the radiologist can examine the breast tissue. Using a local anesthetic, the radiologist makes a small opening in the skin. A sterile biopsy needle is placed into the breast tissue area to be biopsied. Computerized pictures help confirm the exact needle placement. Tissue samples are taken through the needle. It is common to take multiple tissue samples (about three to five).This type of biopsy is used to remove a sample from an area that shows micro-calcifications. These tiny calcium deposits can be evidence of a rapidly changing cell.