[993] Endocervical-Like (Mullerian-Type) Mucinous Borderline Tumors of the Ovary; Are They Mucinous Tumors?

JE Hwang, J Choi, Y-A Paik, YH Lee, JY Shim, K-R Kim. University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea; Pochon Cha University, Seoul, Republic of Korea; University of Ulsan Graduate School, Seoul, Republic of Korea

Background: Endocervical-like (mullerian-type) mucinous borderline tumor of the ovary (EMBT) is currently regarded as synonymous with the mixed-epithelial tumor of the mullerian type or with ovarian seromucinous tumor. It has many clinicopatholgic aspects similar to those of endometrioid tumors rather than to the intestinal type of ovarian mucinous borderline tumors because the former may have various epithelial metaplasia containing a mixture of mullerian-type epithelium, they can be more frequently bilateral, and more frequently the endometrioid tumor is associated with endometriosis as in EMBT. Because of these clinicopathologic findings, we have questioned the validity of the current classification system in which EMBTs are categorized as a subtype of ovarian mucinous tumor.
Design: To find better supporting evidence for categorizing the EMBTs either as endometrioid or mucinous tumors, we performed immunohistochemical stainings for estrogen receptor (ER), progesterone receptors (PR), PTEN, beta-catenin, cytokeratin (CK)7, and CK20 in 18 patients with EMBT, and mutational analysis for KRAS and exon 3 of PTEN using paraffin-embedded tissue sections in 16 cases and 9 cases, respectively.
Results: On the immunohistochemical stainings, all 18 cases showed ER and PR positivities and a consistent CK 7 (+)/CK 20 (-) pattern, both of which were not typical patterns of the mucinous borderline tumor, but closer to those of endometrioid tumor. Immunostaining for beta-catenin showed a cytoplasmic/membranous pattern in all cases without nuclear accumulation, which were different from endometrioid tumors. KRAS mutation at codon 12 were identified in 69% (11/16), and PTEN mutation in exon 3 was not found. It was difficult to interpret the immunohistochemical expression pattern for PTEN.
Conclusions: Although consistent the ER and PR positivities, CK 7 (+)/CK 20 (-) expression patterns and clinicopathologic findings in EMBTs were closer to those of endometrioid tumors, no further clue was identified for categorizing EMBT as an endometrioid tumor as they showed a high frequency of KRAS mutation, absences of PTEN mutation and nuclear accumulation of PTEN protein. However, an additional analysis for PTEN mutation in other area is going on and a meaningful result might wait us.
Category: Gynecologic

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 131, Wednesday Morning