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

Abstract

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]. The overarching goals of the development of the International Academy of Cytology (IAC) System are to stimulate the appropriate use of breast FNAB, improve the reporting of breast FNAB, facilitate the communication between the cytopathologist and the clinical management team, and to promote further research into breast disease utilizing FNAB to further benefit patient care. To do this, the IAC System has established a clear categorization of breast reports into five tiers, each with a clear definition and description, and a specified risk of malignancy (ROM) [1]. The ROM is then linked with management recommendations. These recommendations include several options because it is recognized that the management options available in well-resourced countries are often different to those in low-and middle-income countries, most particularly in the availability of imaging and CNB [1]. The System also crucially emphasizes that breast FNAB relies on the expertise of those performing the biopsy , making the direct smears and interpreting the material on the slides, and this requires good initial and ongoing training and clear communication with the clini-cians managing patients with breast lesions. The process of creating the reporting system was initiated by a core group of cytopathologists with considerable expertise and interest in reporting breast fine needle aspiration cytology, meeting under the auspices of the IAC in May 2016 at the International Congress of Cytol-ogy in Yokohama. Discussions led to the publication of a