Cytology and explanation of AMBS 2004 terminology for reporting cervical cytology

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Cytology

Background

In 1991, the US National Cancer Institute (NCINational Cancer Institute) sponsored a multidisciplinary meeting in Bethesda, Maryland to consider Pap smear terminology. Participants including pathologists, cytotechnologists, gynaecologists and primary care health professionals (predominantly from the USA, but also from other countries) agreed on a consistent system for reporting Pap smears: The Bethesda System 1991 (TBSThe Bethesda System 1991).[1]

NHMRCNational Health and Medical Research Council Australian terminology, 1994

As part of preparing the first National Health and Medical Research Council (NHMRCNational Health and Medical Research Council) 1994 guidelines for the management of women with screen-detected abnormalities,[2] the Australian working party considered the Bethesda terminology and recommended a range of modifications that resulted in a unique Australian terminology system.

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Revisions of The Bethesda System 2001 (TBSThe Bethesda System 2001) and 2014 (TBSThe Bethesda System 2014)

There have been few changes in terminology since 2001.[3][4] In 2014, a smaller working party of cytopathologists, clinicians and epidemiologists reviewed TBSThe Bethesda System 2001, resulting in the 2014 update of The Bethesda System (TBSThe Bethesda System 2014) published in 2015.[5] Changes included additional information on cytology at other anatomical sites, adjunctive HPV testing, immunochemical assays such as dual p16 and Ki67 staining, and computer-assisted interpretation of cytology.

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Australian Modified Bethesda System (AMBSAustralian Modified Bethesda System 2004): current terminology in Australia

Building on the historical NHMRCNational Health and Medical Research Council Australian terminology from 1994, the Australian Modified Bethesda System (AMBSAustralian Modified Bethesda System) was introduced in 2004. AMBSAustralian Modified Bethesda System 2004:

  • incorporated the separation of suspected from confidently predicted low-grade abnormalities
  • reflected a modern understanding of the relationship between HPV infection and cervical cancer and its precursors
  • was compatible with terminology systems used internationally
  • did not mandate distinctions for which there is poor evidence for reproducibility or clinical significance.

There has been no change to the AMBSAustralian Modified Bethesda System since 2004 and it remains the current terminology in Australia. Table 3.1 compares AMBSAustralian Modified Bethesda System 2004 with TBSThe Bethesda System 2001 and TBSThe Bethesda System 2014.

Table 3.1. Comparison of the Australian Modified Bethesda System (AMBSAustralian Modified Bethesda System 2004) and The Bethesda System (TBSThe Bethesda System 2001/2014)

Table3.1 AMBS.PNG

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Explanation of AMBSAustralian Modified Bethesda System 2004 terminology for reporting cervical cytology

Squamous abnormalities

Possible low-grade squamous intraepithelial lesion

The category of possible low-grade squamous intraepithelial lesion (pLSILPossible LSIL in the Australian Modified Bethesda System is broadly equivalent to ASCUS in US Bethesda system.) is to be used when the reporting scientist/pathologist observes changes in squamous cells that may represent a low-grade squamous intraepithelial lesion, but the changes are not so clear-cut as to justify a ‘definite’ diagnosis. This category specifically excludes changes that are within the scope of reactive processes.

Low-grade squamous intraepithelial lesion

The low-grade squamous intraepithelial lesion (LSILLow-grade squamous intraepithelial lesionThe low-grade squamous intraepithelial lesion (LSIL) category is the morphological correlate of productive viral infection. It is to be used when the scientist/pathologist observes changes that would have been described as ‘HPV effect’ or ‘CIN 1’ in the previous Australian terminology and represents part of the previous ‘low-grade squamous epithelial abnormality’ category.) category is the morphological correlate of productive viral infection. It is to be used when the scientist/pathologist observes changes that, pre-AMBSAustralian Modified Bethesda System 2004, would have been described as ‘HPV effect’ or ‘CIN1mild dysplasia’.

Possible high-grade squamous intraepithelial lesion

The category of ‘possible high-grade squamous intraepithelial lesion’ (pHSILPossible HSIL in the Australian Modified Bethesda System is broadly equivalent to ASC-H in US Bethesda system.) is to be used when the reporting scientist/pathologist suspects the presence of a high-grade squamous abnormality, such as CIN2, CIN3 (in the pre-AMBSAustralian Modified Bethesda System 2004 system) or squamous cell carcinoma (SCCSquamous cell carcinoma), but the changes are insufficient to justify a confident cytological prediction of a high-grade lesion.

High-grade squamous intraepithelial lesion

The high-grade squamous intraepithelial lesion (HSILHigh-grade squamous intraepithelial lesionIn the Australian context, HSIL is used to refer to a cytology predictive of a high grade precancerous lesion (AMBS 2004), or histologically confirmed high grade precancerous lesion (HSIL-CIN2 or HSIL-CIN3 as per LAST terminology).) category is the morphological correlate of a true preneoplastic change occurring in squamous cells as a result of HPV infection. It is to be used when the scientist/pathologist observes changes that, pre-AMBSAustralian Modified Bethesda System 2004, would have been described as CIN2 or CIN3.

If, in addition to the presence of a definite intraepithelial high-grade abnormality, there are features that suggest the presence of an invasive component, this should be noted in the ‘specific diagnosis’ section of the report.

Squamous cell carcinoma

The SCCSquamous cell carcinoma category is self-explanatory.

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Glandular abnormalities

Atypical endocervical cells of undetermined significance
Atypical glandular cells of undetermined significance

These categories encompass those changes in glandular cells that the reporting scientist/pathologist believes are outside the scope of a definite reactive process.

It has been well documented that productive HPV infection does not exist in glandular cells, and therefore there is no glandular correlate to the low-grade squamous abnormality. Nevertheless, the morphological changes observed in glandular cells encompass a spectrum of changes. These categories should be used when such changes are insufficient to raise the possibility of a neoplasm, such as AISAdenocarcinoma in situ, but are beyond those accepted as definitely representing a reactive process.

Cells in this category are to be designated as follows:

  • atypical glandular cells when the reporting scientist/pathologist is not sure whether the cells are endocervical
  • atypical endocervical cells when the reporting scientist/pathologist is confident that the cells are endocervical

Possible high-grade glandular lesion

This category is to be used when the reporting scientist/pathologist suspects the presence of a high-grade glandular abnormality such as possible AISAdenocarcinoma in situ, possible endocervical adenocarcinoma or possible endometrial adenocarcinoma, but is unable to make a confident prediction.

Endocervical adenocarcinoma in situ

The endocervical AISAdenocarcinoma in situ category is self-explanatory. The diagnosis is to be used when the reporting scientist/pathologist is confident of the presence of AISAdenocarcinoma in situ.

Adenocarcinoma

The adenocarcinoma category is self-explanatory. The reporting scientist/pathologist has the option of designating whether they believe the adenocarcinoma is endocervical, endometrial or extrauterine in origin.

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References

  1. The 1988 Bethesda System for reporting cervical/vaginal cytological diagnoses. National Cancer Institute Workshop. JAMA 1989 Aug 18;262(7):931-4 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/2754794.
  2. National Health and Medical Research Council. Screening to prevent cervical cancer: guidelines for the management of asymptomatic women with screen detected abnormalities. Canberra: NHMRCNational Health and Medical Research Council; 2005.
  3. Solomon D, Nayar R, editors. The Bethesda system for reporting cervical cytology. Definitions, criteria, and explanatory notes. New York: Springer-Verlag; 2004.
  4. Solomon D, Davey D, Kurman R, Moriarty A, O'Connor D, Prey M, et al. The 2001 Bethesda System: terminology for reporting results of cervical cytology. JAMA 2002 Apr 24;287(16):2114-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/11966386.
  5. Nayar R, Wilbur DC, editors. The Bethesda system for reporting cervical cytology: definitions, criteria and explanatory notes. Third edition. New York: Springer International Publishing Switzerland; 2015.
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