The International Academy of Cytology Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy Cytopathology

Fine needle aspiration biopsy (FNAB) of the breast is globally one of the most commonly performed fine needle biopsies with a long history of successful application, initially in palpable lesions and then in impalpable lesions using ultrasound guidance [1]. In recent times, in many centers and programs in well-resourced countries, FNAB has been largely replaced by core needle biopsy (CNB) because of the perceived benefits of CNB as being able to provide a more definitive answer in proliferative lesions and in diagnosing malignancy, and with a lower insufficient or inadequate rate. To support this perception, publications dating back to the 1990s and early this century are often quoted, from an era before the advent of the routine use of ultrasound-guided FNAB and the use of rapid on-site evaluation [2]. This research is often based on varying cohorts of patients, varying procedural approaches and varying expertise of those performing the FNAB, which is often not stated [2, 3].