The removal of tissue or fluid with a needle for examination under a microscope. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.
Fine-needle aspiration is used when a doctor finds a lump that appears to be a cyst. Removal of fluid from the lump is done using a thin needle and a syringe.
A core needle biopsy uses a needle with a special cutting edge. The core needle is inserted through a small cut in the skin, and a small core of tissue is removed.