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ASCUS terms simplified in Pap smear system. (Bethesda System Revision).

The 2001 revision of the Bethesda system for reporting Pap smear findings has removed much of the terminology that has been criticized as ambiguous.

The changes, the first in a decade, more precisely define the subcategories of atypical squamous cells of undetermined significance (ASCUS). Also, Pap smear specimens are now considered to be either "satisfactory" or "unsatisfactory." The terminology "satisfactory but limited by ..." has been eliminated.

"I think the system will be clearer," said Dr. Leo B. Twiggs, past president of the American Society for Colposcopy and Cervical Pathology. "The changes are minimal, but they should allow for greater clarity."

The great strength of the revisions is that they were put together with input from many different quarters, which was not the case with the 1991 revision, said Dr. Twiggs, associate dean of obstetrics and gynecology at the University of Miami. Forty-three medical specialty societies participated in the revision process.

The American Society for Colposcopy and Cervical Pathology will soon publish new guidelines for the management of cytologic abnormalities and cervical cancer precursors to accompany the Bethesda revisions. Those guidelines will introduce recommendations for incorporating ancillary laboratory tests, particularly based on human papillomavirus testing results.

The revised Bethesda system is expected to be adopted gradually. Most labs will take the basic document and make their own adaptations.

Some of the major changes in the Bethesda 2001 System are:

* Specimen adequacy. Many people thought that reporting specimens as "satisfactory but limited by ..." was an "oxymoron," so that term has been eliminated, said Dr. Diane Solomon, a senior investigator at the National Cancer Institute, who managed the effort. Instead, specimens will be deemed "satisfactory" or "unsatisfactory," and the laboratory will have to report whether unsatisfactory specimens were rejected outright or processed and then found to be inadequate. In that way, physicians will still have feedback that will allow them to know if there is a problem with their collection technique.

* ASCUS. The category of ASCUS has been changed to atypical squamous cells (ASC) with a slightly amended definition: "Cytologic changes suggestive of a squamous intraepithelial lesion that are quantitatively or qualitatively insufficient for a definitive interpretation."

ASC will consist of two types: those of undetermined significance (ASC-US) and those with cytologic changes suggestive of high-grade squamous intraepithelial lesions (HSIL) that lack definitive criteria (ASC-H).

The 1991 system's three-tiered designation for ASCUS results--either "favor reactive," or "favor a squamous intraepithelial lesion," or "not otherwise specified (NOS)--has been found to be subjective and not very consistent, Dr. Solomon said.

ASC results will probably be a somewhat smaller percentage of Pap smear results, compared with ASCUS. The system recommends that pathologists downgrade those reports previously called "ASCUS, favor reactive," because the potential for a squamous intraepithelial lesion is low in those cases. Instead, those cases should be listed under a section for "other nonneoplastic findings," and ASC will encompass only those cases previously called "ASCUS, NOS," and "ASCUS, favor neoplastic."

Of the two new subcategorizations, ASC-US will probably comprise 90%-95% of the ASC category, and ASC-H will comprise 5%-10%.

Recommendations for the management of ASC-US will depend on whether ancillary testing detects the presence of a worrisome human papillomavirus type.

* Benign cellular changes. This category is eliminated. Instead, reports previously described with this term will fall under the category of "negative for intraepithelial lesion or malignancy." Under the interpretation for this category, the lab will report whether there were "organisms" (instead of infections) or "other nonneoplastic findings," which will include reactive cellular changes, glandular cells status post hysterectomy, and atrophy.

* Atypical glandular cells of undetermined significance (AGUS). This terminology has been eliminated, largely to avoid confusing the acronym with ASCUS. Also, "AGUS, favor reactive," was thought to give a false sense of security given that 5%-39% of cases turn out to be high-grade lesions on follow-up. Instead, glandular cell abnormalities will fall under the heading of "epithelial cell abnormalities." Atypical glandular cells will be qualified as being of endocervical or endometrial origin, and will be classified as "favor neoplastic" or left unqualified.

There will also be a place to specifically note "endocervical adenocarcinoma in situ." The criteria for identifying a finding as endocervical adenocarcinoma in situ are fairly reproducible and have predictive meaning, Dr. Solomon said. For more information on the Bethesda System 2001, go to
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Title Annotation:atypical squamous cells of undetermined significance
Author:Kirn, Timothy F.
Publication:Internal Medicine News
Date:Dec 15, 2001
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