[1241] Reproducibility and Cancer Risk Stratification of Endometrial Samplings Utilizing World Health Organization and Endometrial Intraepithelial Neoplasia Classifications

Mary M Tomic, Nicole A Pele, John W Bishop, Eric C Huang. University of California, Davis Medical Center, Sacramento, CA

Background: Endometrial carcinoma is the most common malignant tumor in the female genital tract. Two diagnostic schemas are currently used for identifying premalignant disease. The more widely practiced World Health Organization (WHO) classification is categorized into typical hyperplasias (simple or complex hyperplasia without atypia) and atypical hyperplasias (simple or complex hyperplasia with atypia). The more recent Endometrial Intraepithelial Neoplasia (EIN) criteria include: 1) area of glands exceeds that of stroma, 2) nuclear and/or cytoplasmic features of epithelial cells differ between architecturally abnormal glands and normal background glands, 3) maximum linear dimension exceeds 1 mm, and 4) exclusion of mimics/cancer. This study examines the diagnostic reproducibility and cancer risk stratification under both systems.
Design: An institutional retrospective review of all endometrial samplings from 2008 to 2010 by the Pathology Laboratory Information System identified 40 cases with a diagnosis of hyperplasia by the WHO classification with clinical follow-up. A randomized blinded re-review of all cases was performed by two gynecologic pathologists, each was asked to categorize individual cases under the WHO (benign, simple hyperplasia with or without atypia, and complex hyperplasia with or without atypia) and EIN (benign, gland crowding, and EIN) classifications on separate occasions (1 month apart). Inter-observer agreement and risk stratification were analyzed.
Results: Clinical follow-up revealed endometrial carcinoma in 28% (n=11) of these study cases. The inter-observer agreement for EIN and WHO diagnostic schemas was 73% and 58%, respectively. The sensitivity of predicting cancer risk was 95.5% for EIN and 77.3% for WHO, and the negative predictive value was 97.7% for EIN vs. 90.9% for WHO. Under the EIN criteria, the only case that had a cancer outcome without an EIN diagnosis was categorized as gland crowding.
Conclusions: This study demonstrates that the EIN criteria have greater inter-observer reproducibility, higher sensitivity and better negative predictive value when compared to the WHO classification. In addition, it highlights that the rare cases sub-diagnostic of EIN, while having low risk of cancer occurrence, require appropriate clinical follow-up.
Category: Gynecologic & Obstetrics

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 131, Tuesday Morning

 

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