[1209] BAF250a (ARID1A) Expression in Ovarian Clear Cell Adenocarcinoma with an Adenofibromatous Component

Kyoko Nishikimi, Takako Kiyokawa, Shinichi Tate, Masami Iwamoto, Takashi Kisimoto, Kazunori Fugo, Makio Shozu. Chiba University Graduate School of Medicine, Chiba, Japan

Background: Ovarian clear cell adenocarcinoma (CCA) is frequently associated with endometriosis (EMosis), and less often with an adenofibromatous component (AF). Recent studies have suggested that mutation of the ARID1A gene and loss of the corresponding protein BAF250a as a frequent event in CCA. Approximately half of CCA have an ARID1A mutation resulting in loss of BAF250a expression in immunohistochemistry. Since an ARID1A mutation has been also found in EMosis adjacent to CCA but not in distant EMosis, it may be an early event in neoplastic transformation. This study was conducted to clarify BAF250a expression in AF-related CCA and to compare with that in EMosis-related CCA.
Design: Ninety-three cases of CCA surgically treated between 2000 and 2012 were included in the study. All H-E slides of the ovarian tumors were reviewed for the presence of AF and EMosis associated with carcinoma. Immunohistochemical staining for BAF250a was performed to exam its expression in carcinoma, and in AF and/or EMosis concurrent with CCA. Nuclear immunoreactivity of more than 90% of the cells was considered positive.
Results: Of 93 cases, 17 were associated with AF alone, 45 with EMosis alone, 18 with both AF and EMosis, and 13 with neither AF nor EMosis. BAF250a was positive in AF and EMosis in all 80 cases with these components. BAF250a was negative in carcinoma in 53/93 (57%): 6/17 (35%) of AF alone, 30/45(67%) of EMosis alone, 8/18 (44%) of AF+EMosis, and 9/13(69%) of both negative CCA. Loss of BAF250a expression was significantly less frequent in AF alone CCA compared to that of EMosis alone CCA (p=0.026, Chi-Square test, Pearson).
Conclusions: Our results suggest that genetic background of carcinogenesis is different between AF-related and EMosis-related CCA in terms of an ARID1A mutation.
Category: Gynecologic & Obstetrics

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 181, Wednesday Morning


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