Chapter-06 Squamous Intraepithelial Lesions and Invasive Squamous Cell Carcinoma

BOOK TITLE: Handbook of Cervical Cytology: Special Emphasis on Liquid-based Cytology

1. Dey Pranab
Publishing Year
Author Affiliations
1. Postgraduate Institute of Medical Education and Research, Chandigarh, India
Chapter keywords
Squamous intraepithelial lesion, SIL, invasive squamous cell carcinoma, low-grade squamous intraepithelial lesion, LSIL, high-grade squamous intraepithelial lesion, HSIL, nuclear hyperchromasia, liquid-based cytology, LBC


This chapter presents discussion on squamous intraepithelial lesions and invasive squamous cell carcinoma. Squamous intraepithelial lesion (SIL) is classified as low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL). The Bethesda system (TBS) 2001 has classified squamous intraepithelial lesions in two tier system. The logic behind the two tier grading system are: most of the LSIL does not progress to higher grade and either persist or regress and it is expected that two tier grading is more reproducible than three tier grading (CIN 1, 2, and 3). LSIL encompasses both human papillomavirus (HPV) induced changes and cervical intraepithelial lesions grade 1 (CIN 1), whereas HSIL includes cervical intraepithelial lesions grade 2 (CIN 2) and cervical intraepithelial lesions grade 3 (CIN 3). The majority of LSIL is caused by low risk HPV 6 and 11. In case of LSIL the lower one-third of the cervical squamous epithelium shows dysplastic cells. In case of HSIL the histopathology section of the cervix shows involvement by dysplastic cells by more than basal one-third of the epithelium. The cells show moderately enlarged and pleomorphic nuclei. Distinguishing cytological features of LSIL versus HSIL are also covered in this chapter.

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