A breast biopsy is a diagnostic test in which a small sample of tissue is taken from a suspicious area within the breast for close examination under a microscope. While diagnostic imaging studies can help visualize a lump or lesion within the breast, a biopsy is the only way to know for sure whether cancer is present – however, many breast biopsies reveal benign (non-cancerous) conditions. There are several ways that a breast biopsy may be taken. These include a fine needle aspiration biopsy, in which a very thin needle is directed to the suspicious area and used to withdraw a small amount of tissue. Sometimes your doctor will employ ultrasound to help locate the specific area for this test, in which case it is called an ultrasound-guided biopsy. Other types of breast biopsy performed via a needle include a core needle biopsy and a stereotactic core needle biopsy. An “open” biopsy is another method for retrieving a breast tissue sample and usually involves removing the entire lump or suspicious area.