Atypical glandular cells (AGC): Cytology of glandular lesions of the uterine cervix

The Pap smear is a well-known screening tool for squamous lesions of the uterine cervix. However, its screening role in glandular lesions is less effective. The incidence of squamous cell carcinoma of the cervix has dramatically decreased with the advent of Pap smear and recent understanding related to HPV carcinogenesis of cervical cancers including the advent of HPV vaccines. However, in recent years, the incidence of glandular abnormalities, diagnosed on Pap smears, has increased with greater sensitivity and precision. The incidence of atypical glandular cells (AGC) is approximately 0.18–0.74% of all cervical smears with a reported prevalence of 2.5% among all Pap smears. A high degree of suspicion, good clinical history, and the presence of diagnostic cytomorphological findings are essential for the proper interpretation of glandular cell abnormalities. A methodical approach to evaluate Pap smear greatly helps interpretation and avoids the diagnostic pitfalls. The Bethesda System for reporting cervical cytology has categorized glandular cell abnormalities into various categories as follows: A. Endocervical adenocarcinoma in situ (AIS). B. Atypical glandular cells (AGCs). a. Endocervical cells: a1 NOS or specify in comments; a2 Favor neoplastic. b. Endometrial cells: NOS or specify in comments. C. Adenocarcinoma (AdCa). a. Endocervical. b. Endometrial. c. Extrauterine. d. NOS. Subtle differences in quantitative and qualitative cytologic features are essential for distinguishing one category from another. In this chapter, we highlight an organized approach for the interpretation of glandular abnormalities in Pap smear for our readers. This is an overview of the Bethesda categories, the reason for classification, and differential diagnosis with key characteristic features. An approach to the methodical evaluation of hyperchromatic crowded groups is discussed with key cytomorphologic differences. An algorithmic approach is suggested to facilitate the interpretation of various AGC categories.