October 31, 2011 (Las Vegas, Nevada) — Pap tests can detect endometrial pathology, with a 75.8% positive predictive value (PPV) for endometrial adenocarcinoma, according to research presented here at the American Society for Clinical Pathology 2011 Annual Meeting.

The Bethesda System 2001 does not recommend the subclassification of atypical endometrial cells because a lack of well-defined criteria. However, researchers at Henry Ford Hospital in Detroit, Michigan, have pushed that envelope a bit.

"Our division advocates that if a Pap smear shows obviously malignant cytologic features of endometrial adenocarcinoma, we should provide the diagnosis of positive/suspicious instead of atypical. This distinction could provide clinicians with much more sensible information in terms of how they follow their patients. Although this may carry some false positive results, the patients may benefit from proper management in a timely manner," presenter Linda Szymanski, DO, pathology resident at Henry Ford Hospital, told Medscape Medical News.

This study was undertaken to determine the value of the Pap test in detecting endometrial pathology and the potential pitfalls of a false positive diagnosis.

The researchers conducted a retrospective analysis of 153 patients with a diagnosis suspicious or positive for endometrial adenocarcinoma from 2005 to 2011. All selected cases were followed up surgically.

Diagnostic criteria were based on nuclear size, nuclear irregularity, chromatin pattern, presence of nucleoli, cytoplasmic vacuolization, and tumor diathesis.

In all, 132 cases (age range, 25 to 95 years) had significant pathologic findings: 116 cases of endometrial adenocarcinoma, 14 cases of endometrial hyperplasia, and 2 cases of benign endometrial polyp. There were 21 negative pathology findings (age range, 43 to 83 years).

A second review of the 21 false-positive cases and the 2 benign endometrial polyp cases revealed nuclear hyperchromasia, nucleoli, and cytoplasmic vacuolation, but there was no significant nuclear enlargement or tumor diathesis. Overall, the high-yield cytologic criteria generated a 75.8% PPV for detecting endometrial adenocarcinoma (including all positive and suspicious diagnoses).

"When we eliminated the suspicious diagnosis, we achieved a PPV for outright positive diagnosis of 90%," said Dr. Szymanski. Despite this success, the researchers say that the Pap test is not an effective screening test for endometrial pathology.

"We learned that when there is a lack of significant nuclear enlargement, we should take a step back. A diagnosis of 'atypical endometrial cells present' may be more appropriate than a 'suspicious or positive' diagnosis," said Dr. Szymanski.

She also pointed out that Pap test results suspicious or positive for endometrial adenocarcinoma might not be readily transferable to other institutions. "This is what we have been doing here for quite a while with continuous cyto/histo correlation and clinical follow-up. Therefore, we feel comfortable and confident in making these diagnoses. Further investigation and research are needed, and every center should gauge this based on their own standard of practice and level of expertise," said Dr. Szymanski.

The study gives useful insight into Pap test results, according to Shelly A. Semrad, CT, anatomic pathology practice manager at Regions Hospital in St. Paul, Minnesota, who attended the session. "It's a really interesting correlation to look at. They had good positive predictive value with their results. Endometrial [carcinoma] isn't something you typically use a Pap smear to find, but it's another reason to use it," Ms. Semrad told Medscape Medical News.

Dr. Szymanski and Ms. Semrad have disclosed no relevant financial relationships.