Liquid-based cytology: a 25-year bridge between the pap smear and molecular cytopathology.

Since its introduction, many laboratories have started to apply LBC to exfoliative and aspiration nongynecological cytology, aiming to exploit the same advantages on different samples. In fact, LBC is well suited to meet the requirements of ancillary techniques and their routine application in pathology laboratories, with specific reference to procedure standardization, purification and storage of diagnostic material. As a matter of fact, method standardization and the opportunity to store cells are significant benefits of nongynecological LBC, which can be used in different organs for different applications. Whereas the advantages of gynecological LBC have been immediately obtained on respiratory cytology [5] , the same features of LBC have limited, in some cases, the diagnostic criteria typical of traditional cytology. For instance, the additional value of collected material and the time saved from cytological assistance, mainly in CT-, EUSand EBUS-guided FNA techniques, as well as other time-consuming FNA techniques, may hamper or even exclude the possibility of performing rapid on-site evaluation and the immediate repetition of inadequate samples. Moreover, at a diagnostic level, the clean and purified background that improves and enhances cellular details in gynecological LBC or in bronchial washingbrushing in thyroid and breast FNAs eliminates or reLiquid-based cytology (LBC) was first applied to gynecological cytology almost 25 years ago [1] . A few years before, the conventional Pap smear, after decades of unquestionable success proven by the drop in morbidity and mortality rates due to cervical carcinoma in the countries that had adopted it in national screening programs, met some criticism in the international media. Because of a reported rate of false negatives and some inefficiencies, the Pap test was openly discussed and criticized in journals that were not usually devoted to specific scientific issues [2, 3] . The following and timely introduction of LBC aimed to improve the efficiency of gynecological cytology through procedure standardization, sample quality improvement, screening support and speedup, and quality control, as well as by storing the residual material for possible repetitions and/or the application of ancillary techniques. Whereas LBC seems to be neither more sensitive nor more specific than the conventional Pap test, mainly in the detection of high-grade cervical intraepithelial neoplasia [4] , overall it achieved the above-reported goals, with its additional costs being compensated by reported advantages. As a consequence, LBC has replaced the conventional Pap smear in many laboratories in industrialized countries and promises to survive the era of cervical HPV testing and vaccination. Published online: November 25, 2014