FNA or puncture with fine needle aspiration is a test used in Pathology in which it draws or aspirates, with a fine needle, a total or partial sample of tissue or organs material to be analyzed under a microscope. Using ultrasound, magnetic resonance imaging or computed tomography the right place for the puncture is chosen, it is disinfected and the area is anesthetized for later biopsy. At all times the needle is followed by imaging tests to avoid blood vessels and the possibility of bleeding. Puncture of Fine Needle Aspiration allows for cells or tissue pieces. When cells are extracted only it allows a cytological study, which means that the pathologist can determine whether the cells are benign, malignant or have changes, but can not determine whether a tumor or the degree of malignancy exists. When pieces of tissue are obtained it may carry out a histological study, so that if you can distinguish the type of existing cancer and its degree of malignancy.