[1075] Proliferative Activity in Serous Tubal Intraepithelial Carcinoma Compare to Adjacent Normal Tubal Epithelium and Concurrent High-Grade Serous Carcinoma.

Elisabetta Kuhn, Robert J Kurman, Ann E Smith Sehdev, Ie-Ming Shih. Johns Hopkins Medical Institutions, Baltimore, MD; Lagacy Health Services, Portland, OR

Background: Serous tubal intraepithelial carcinoma (STIC) has been recently recognized as a potential precursor lesion of ovarian high-grade serous carcinoma (HGSC) but reproducibly diagnosing it, even among expert gynecologic pathologists, can be very difficult. Although proliferative activity as indicated by the Ki-67 labeling index has been reported to be increased in STICs, a direct comparison of the Ki-67 index in the STIC to normal-appearing fallopian tubal epithelium (FTE) and the associated ovarian HGSC in the same patient has not been described. In this study we compare the Ki-67 index of FTE, STIC and ovarian HGSC in the same patient to evaluate whether Ki-67 staining can assist in the diagnosis of a STIC.
Design: A total of 33 STICs were analyzed, and among them 29 were associated with concurrent HGSC. Nine normal fallopian tubes from postmenopausal patients without neoplastic diseases were included as controls. Histological diagnosis of STICs was made according to previously reported morphological criteria (1). The Ki-67 index (using the Mib-1 antibody) was determined by calculating the percentage of cells showing nuclear immunoreactivity, in three random 20X-power fields. A minimum of 250 cells was counted.
Results: Immunoreactivity for Ki-67 in FTE was restricted to a few scattered cells and no statistically significant difference was found between patients with and without HGSC (p>0.05). On the other hand, both STICs and HGSCs had significantly higher Ki-67 indices than normal FTE (p< 0.0001). STICs were uniformly positive for Ki-67, with an index raging between 11.7%-71.1%. Ki-67 immunoreactivity was predominantly located in the basal layer in STICs. Based on the findings in 42 FTE specimens, we propose to use the mean Ki-67 index (2.4%) + 3 standard deviations (2.8% x 3) which approximated 10% as the cutoff to distinguish STICs (including p53 negative ones) from normal FTE (100% sensitivity and 93% specificity). In 29 cases with concurrent ovarian HGSC, the Ki-67 labeling index was higher in STIC vs. HGSC in 12/29 (41.4%) while it was lower in 17/29 (58.6%) (p=0.55).
Conclusions: Our data indicate that STICs have a high Ki-67 index similar to HGSC and that a Ki-67 >10% is a useful adjunct in making the diagnosis.
1. Kuhn, E., et al., Shortened telomeres in serous tubal intraepithelial carcinoma: an early event in ovarian high-grade serous carcinogenesis. Am J Surg Pathol. 34(6): p. 829-36.
Category: Gynecologic & Obstetrics

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 130, Wednesday Morning


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