They will then undergo ultrasound-guided fine-needle aspiration (FNA). Classical needle biopsy techniques will be used, with patients lying on their backs with their necks in hyperextension. An initial ultrasound scan will be used to determine the site or sites at which the needle should be inserted. Following extensive disinfection of the skin of the neck, the needle will be inserted under ultrasound guidance. The needle will be moved gently backwards and forwards and displaced radially in a clockwise direction to recover cellular material by capillarity. The material recovered will be diluted in 30 ml of CYTOLYT (Hologic), a transport medium for the recuperation of cells in liquid media. In general, several (two or three) passages of the needle are required for a given nodule. It is possible to carry out FNA on up to three nodules in a single session. For each passage, a new, sterile, single-use needle will be used. The insertion of each needle will be preceded by an ultrasound scan.