a procedure to remove fluid, cells, or tissue with a hollow needle so that it can be looked at under a microscope. The main types of needle biopsy are fine needle aspiration (FNA) and core biopsy. FNA uses a thin needle to draw up (aspirate) fluid or small tissue pieces from a cyst or tumor. A core needle biopsy uses a thicker needle to remove a core of tissue from a tumor. See also biopsy, core needle biopsy, fine needle aspiration biopsy, needle aspiration.