The sampling of breast tissue with a cutting needle, 18 gauge or larger, to give a tiny cylinder of tissue for histological examination. This technique may involve a mechanical device to drive the cutting needle.
"A core biopsy or wide bore needle biopsy (WBN) is a procedure used during the assessment process to obtain a preoperative diagnosis for a woman who potentially could have breast cancer. The procedure involves inserting a wide bore needle into the area of uncertainty in a womans breast, sometimes under ultrasound or x-ray control, and withdrawing a core of tissue from that area. The core of tissue is then sent to the histopathology laboratory for histological examination by a pathologist." -- NHSBSP 47.