Classification of cervical abnormalities

Using the Bethesda System as a foundation, the Australian working party developed a unique Australian terminology system for squamous and glandular lesions called the Australian Modified Bethesda System (AMBS 2004). Refer to tables 1 and 2 (below).

Squamous abnormalities

Squamous abnormalities are classified into:

  • possible or definite low-grade squamous intraepithelial lesions (LSIL or HPV +/-CIN 1)
  • possible high-grade squamous intraepithelial lesions (where the presence of a high-grade abnormality such as CIN 2, CIN 3 or squamous cell carcinoma cannot be excluded)
  • high-grade squamous intraepithelial lesions (HSIL, CIN 2 or CIN 3)
  • squamous cell carcinoma.

The cervical cytology classification system assists the medical scientist and pathologist to classify the cervical cellular changes to allow appropriate follow-up recommendations and clinical management.33

The classification of squamous intraepithelial lesions is characterised by abnormal cellular proliferation and maturation, together with nuclear atypia.

In LSIL, the changes predominantly occupy the lower third of the epithelium and marked HPV cytopathic effects (koilocytosis) are often seen.

In HSIL, the changes inhabit the lower two thirds of the epithelium (CIN 2), or the full thickness of the epithelium (CIN 3), and the nuclei are hyperchromatic and irregular.

HSILs are also characterised by detectable high risk (HR) HPV DNA and chromosomal instability.7

Table 1: The Australian Modified Bethesda System (AMBS 2004) for squamous abnormalities.
AMBS 2004  Incorporates
Possible low-grade squamous intraepithelial lesion Non-specific minor squamous cell changes. Changes that suggest, but fall short of, HPV/ cervical intraepithelial neoplasia (CIN) 1
Low-grade squamous intraepithelial lesion (LSIL) HPV effect, CIN 1
Possible high-grade squamous intraepithelial lesion Changes that suggest, but fall short of, CIN 2, CIN 3 or squamous cell carcinoma
High-grade squamous intraepithelial lesion (HSIL) CIN 2, CIN 3
Squamous cell carcinoma Squamous cell carcinoma

Glandular abnormalities

Although adenocarcinoma in situ (AIS) is defined as a pre-invasive cervical lesion, natural history studies to confirm its potential to progress are lacking.34 AIS is much less commonly diagnosed than the corresponding squamous preinvasive lesions.11

No terminologies of glandular lesions with lower degrees of nuclear atypia have been established due to rarity in biopsies.35-37

Table 2: AMBS 2004 for glandular abnormalities.33
AMBS 2004 Incorporates
Atypical endocervical cells of undetermined significance Non-specific minor cell changes in endocervical cells
Atypical glandular cells of undetermined significance Non-specific minor cell changes in glandular cells
Possible high-grade glandular lesion Changes that suggest, but fall short of, AIS or adenocarcinoma
Endocervical adenocarcinoma in situ Adenocarcinoma in situ
Adenocarcinoma Adenocarcinoma

References

Refer to clinical references for cervical carcinoma information.

More information

WA Cervical Cancer Prevention Program (WACCPP)

Opening hours: 8.00am – 4.30pm, Monday to Friday
Phone: 9323 6788 or 13 15 56 (cost of a local call)
Email: cervicalscreening@health.wa.gov.au
Fax: 9323 6711
Address: 1070 Hay Street, West Perth WA 6005

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WA Cervical Cancer Prevention Program