Disorders of the Cervix

• The disorders of the cervix will be discussed
• The study notes were prepared by Simón Quetzalcoatl Rodríguez and Lara MD, PhD.

Cervix Facts

• Cervical mucosa is 2 to 3 mm thick
• Contains large branched glands
• Cervical mucosa differs dramatically from the uterine endometrium
• The ectocervix is covered with stratified squamous epithelium (SSE)
• The endocervix is covered by a mucus-secreting columnar epithelium (SCE)
• An abrupt transition between squamous and columnar epithelium occurs in the transformation zone

Metaplasia

• Metaplastic changes in the transformation zone are precancerous lesions of the cervix
• A change in form representing an adaptive and reversible response to persistent injury of the epithelium
• Caused by chronic infections such as HPV
• Leads to reprogramming epithelial stem cells to differentiate into a new cell lineage
• Manifested as a replacement of simple columnar with mature stratified squamous epithelium in the endocervix

Pap Smear

• According to (2014-2018) CDC statistics, 8 new cervical cancer cases and 2 deaths per 100,000 women were reported in the US
• Cervical Pap smear is optimal for screening precancerous lesions
• Best reported using unified reporting system like the Bethesda System
• The vaginal walls are held apart with a speculum, so cells from cervix can be collected with a soft spatula
• Sampled cells, preserved in solution or smeared on a slide, are then checked under a microscope

Bethesda System

• Cytologic findings are described as "Epithelial cell abnormality: Squamous"
• This includes the squamous intraepithelial lesion (SIL) category encompassing a spectrum of lesions
• Spectrum includes low-grade SIL (LSIL) to high-grade SIL (HSIL), and ultimately invasive squamous cell carcinoma
• Depending on qualitative and quantitative factors, some equivocal features fall under "Atypical Squamous Cells" (ASCs)
• ASCs are subdivided into:
  • "Atypical Squamous Cells of Undetermined Significance" (ASC-US)
  • "Atypical Squamous Cells-HSIL cannot be excluded" (ASC-H), based on the suspected underlying lesion LSIL vs HSIL

Intermediate Cell Nuclei (ICN)

• One of the important diagnostic features used when interpreting epithelial cell abnormality
• Based on nuclear enlargement compared with the size of ICN
• Nucleoli are usually sharply delineated eosinophilic round structures
• Round to oval in shape
• Well defined
• Eosinophilic (usually) to basophilic

Bethesda System & LSIL

• Low-grade squamous intraepithelial lesion (LSIL) refers to morphologic changes along the lower end of the spectrum of SIL
• About 1.7% of all PAPs are interpreted as LSIL, whose majority (>80%) are positive for HR-HPV

Koilocytes

• One of the major cytomorphologic and easily identifiable LSIL feature
• Show raisinoid nuclei with sharply delineated perinuclear cytoplasmic clearing and irregular outline with focal angulations
• Nuclei display enlargement, hyperchromasia, and membrane irregularities
• Binucleation and multinucleation is frequent

LSIL Cells Cytomorphological Features

• Nuclear enlargement (nuclear size more than 3 times ICN) with intermediate/superficial cell-like cytoplasm with relatively low N/C ratio
• Nuclear hyperchromasia with occasional binucleation
• Variably irregular nuclear contours with sharp angulations and indentations
• Coarse chromatin
• Possible increased keratinization as dense orangeophilia (atypical parakeratosis)
• Sharply demarcated perinuclear cytoplasmic clearing (koilocytosis) with an irregular outline with focal angulation characteristic of HPV cytopathic effect
• Immature metaplastic cytoplasm (small atypical parakeratotic [SAPK] cells) may be difficult to distinguish from ASC-H or HSIL, which may involve eosinophilic dysplasia or acanthotic component of condylomatous lesion

Bethesda System & High Grade Squamous Intraepithelial Lesion (HSIL)

• HSIL refers to morphologic changes associated with the higher end of the SIL spectrum
• includes both CIN 2 and CIN 3 (with CIS)
• About 0.3% of all PAPS are interpreted as HSIL, almost all (95%) of which are HR-HPV positive
• HSIL has a higher rate of progression to cancer and a lower rate of regression; long-term progression estimated at 30% for 30 years
• Under low-power view, two-dimensional sheets of cells or hyperchromatic crowded groups (HCGs) seen as a syncytium can be identified
  • CIN 2 cells can be checkerboard pattern
  • CIN 3 cells as the syncytial aggregates

Features of HSIL Cells

• Singly scattered HSIL cells, as sheets with checkerboard pattern, or in syncytial aggregates of HCG
• Typically HSIL cells are smaller and show less cytoplasm than LSIL cells
• High Nucleus/cytoplasm ratio compared to LSIL
• Irregular nuclear contours with frequent indentations and longitudinal nuclear grooves
• Usually hyperchromatic nuclei, but occasionally normochromic or also hypochromatic
• Typically, evenly distributed coarse chromatin, but sometimes fine
• Nucleoli are generally absent but may be seen along the periphery of HSIL cell groups in cases with endocervical glandular extension
• Cytoplasm variable:
  • from “immature” dense “metaplastic" with focal vacuolation to occasionally densely keratinized cytoplasm
  • not like adenocarcinoma in situ [AIS] with lacy and delicate cytoplasm

Cervical Intraepithelial Neoplasia (CIN)

• Histologic changes are described as "cervical intraepithelial neoplasia (CIN)"
• CIN has three degrees of severity
  • CIN 1 is a low-grade lesion referring to mildly atypical cellular changes in the lower third of the epithelium
    • Has human papillomavirus (HPV) cytopathic effect (koilocytotic atypia)
  • CIN 2 is a high-grade lesion referring to moderately atypical cellular changes confined to the basal two-thirds of the epithelium (formerly called moderate dysplasia) with preservation of epithelial maturation
    • Variability exists
  • CIN 3 is a high-grade lesion referring to severely atypical cellular changes encompassing most of the epithelial thickness
    • Fully thickness lesions with previous terms, severe dysplasia or carcinoma in situ
    • Due to poor reproducibility of CIN 2, CIN 2 and 3 are often classified together as an entity

HPV and Cervical Cancer

• Causal relationship between oncogenic HPV types and cancer first established for cervical cancer
• Cervical cancer is the leading HPV-associated cancer worldwide, with over half a million cases per year

HPV

• Small, double-stranded, circular DNA viruses, genome 8 kb
• Strictly epitheliotropic infecting mucosal and cutaneous tissues
• Currently, 227 HPV types are known to persist in the human population
• About 40 alpha-types were shown to be the causative agents of 750,000+ cases of human malignancies annually
• The most investigated cancer-causing HPV types are HPV-16 and HPV-18 responsible for over 80% of the world's cervical burden
• HPV-16 appears to be the major cancer-causing HPV type also linked to Head and neck cancers

E6 and E7

• E6/E7 oncogene integration in the host genome results in their uncontrollable and upregulated protein expression
• This is considered to be key step in HPV-mediated carcinogenesis
• Cellular expression shown to be active many years after event
• Required for maintaining transformed cervical tumour phenotype, as well as perpetual proliferation of cells

Questions about the transformation zone, metaplasia, and interpretation of Pap smear results using the Bethesda System. Covers HPV infection and appropriate management steps based on Pap smear findings. Also touches on the characteristics of the endocervix.