The text of this second edition has been completely revised, planned and written with two goals in mind: to help those learning cytopathology for the first time, including pathology residents, fellows, and cytotechnology students, and to provide a resource for those who have experience in cytopathology but are faced with a difficult diagnostic dilemma. It reflects the fact that diagnostic criteria have become more refined, some types of aspiration are now more common, and terminology has changed.