[1273] Papillary Mucinous Metaplasia as a Possible Precursor of Low-Grade Mucinous Adenocarcinoma of the Uterine Corpus

Su-Hyun Yoo, Bong Hee Park, Dong-Eun Song, Jene Choi, Hee Jeong Kim, Kyu-Rae Kim. University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea; Mizmedi Hospital, Seoul, Republic of Korea

Background: Mucinous adenocarcinoma is an uncommon type of malignant neoplasm of endometrium, which includes specific variants such as low-grade mucinous adenocarcinoma, and microglandular adenocarcinoma simulating microglandular endocervical hyperplasia. However, their precursor lesions have not yet been identified. During the review of endometrial lesions in postmenopausal women, we have noticed that endometrial mucinous metaplasias have variable degrees of proliferative change with or without intraglandular micropapillary architecture, some of which show histological similarity to the recently described low grade mucinous adenocarcinoma. The histological similarity raised the suspicion that papillary mucinous metaplasia could be a precancerous lesion of low-grade mucinous adenocarcinoma.
Design: We have searched 21 endometrial mucinous metaplasia from women in age of 50 or older during 3.5 year periods. In an effort to explain the pathogenetic significance of mucinous metaplasia without intraglandular papillary tufts (designated as simple muinous metaplasia, n=7) and with papillary tufts (designated as papillary mucinous metaplasia, n=14), we analyzed immunohistochemical expressions of estrogen (ER) and progesterone receptors (PR), Ki67, PTEN, β-catenin, P16, P53, and PAX2 using paraffin embedded tisssue sections. In addition, mutational analyses for KRAS and PTEN were performed in 7 simple mucinous metaplasia and 9 papillary mucinous hyperplasia using paraffin embedded tissue to explain the relationship with endometrial adenocarcinoma.
Results: Intraglandular papillary tufts in papillary mucinous metaplasia showed selectively decreased or lack of PAX 2 and PR expressions, and an increased expression of P16 compared to the surrounding glandular epithelium or to the simple mucinous metaplasia. PTEN expressions in glandular epithelium were decreased in both groups. Papillary mucinous metaplasia showed KRAS mutation of codons 12 or 13 in 89% compared to 14% in simple mucinous metaplasia. Ki-67 labeling index, ER, and β catenin expressions were not significantly changed in both groups.
Conclusions: Although we could not directly compare these results of mucinous metaplasia with those of mucinous adenocarcinomas, immunohistochemical expressions, mutational status, and histological similarity suggest that papillary mucinous metaplasia could be a precancerous lesion of endometrium, especially of mucinous adenocarcinoma.
Category: Gynecologic & Obstetrics

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 194, Monday Morning


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