Challenging lesions in cervical cytology: The elusive HSIL

Cervical cytology has been an integral part of cervical cancer screening since the mid-20th century with the implementation of screening protocols utilising Pap testing. During that time, cervical cancer has gone from the leading cause of cancer deaths in women to not even appearing in the top 10 causes of US cancer deaths. However, despite its long and widespread use, cervical cytology remains a diagnostically challenging area in the practice of cytopathology. Of particular importance for diagnosticians is the accurate diagnosis of high-grade squamous intraepithelial lesions (HSILs), given the significant risk of progression to invasive cervical cancer and the importance to patient management. Therefore, this review is presented in order to highlight the diagnostic features of HSIL, its various appearances, and important benign and neoplastic differential considerations with an emphasis on morphological clues that can aid in distinguishing between these different processes.