PAX8: A Sensitive Marker To Identify Cancer Cells of Gynecologic Origin in Pelvic Washings.
Nisreen Abushahin, Haiying Zhang, Li Xiang, Danial Lee, Oluwole Fadare, Wenxin Zheng. University of Arizona College of Medicine, Tucson; Vanderbilt University School of Medicine, Nashville, TN
Background: Pelvic washings are a routine component of the staging procedures for many gynecologic tract cancers, and the correct interpretation of the pathologic changes in the resultant specimens may have a direct impact on post-surgical patient management. However, inconclusive changes in washing specimens are not infrequently encountered. PAX8 is a nuclear transcription factor that has recently been recognized as a useful biomarker in distinguishing ovarian carcinomas from breast cancers and mesotheliomas. The objective of this study was to assess the diagnostic utility of PAX8 in pelvic washing specimens.
Design: Pelvic washing samples with cell blocks from 53 patients with a variety of neoplastic and non-neoplastic pathologic processes were retrieved. These included 15 “positive”, 28 “atypical or suspicious but non-diagnostic”, and 10 “negative” cases based on cytology reports. Immunohistochemical studies for PAX8 and Calretinin were performed on all cases. Ovarian cancer, which has a known high level of PAX8 expression, served as positive controls. The final diagnosis for each case was based on the conventional gold standard, which was based on the totality of all clinicopathologic findings.
Results: All “positive” cases were PAX8 + and Calretinin -. All “negative” cases were PAX8 -. The group with inconclusive diagnoses showed the following distribution of findings: 14 PAX8 +, 13 PAX8 – and 1 non-contributory. The 14 positive cases included ovarian high-grade serous carcinoma (7), ovarian low-grade serous carcinoma (2), serous borderline tumor (2), Sertoli-Leydig cell tumor (1), endometriosis (1), and tubal torsion (1). The 13 negative cases included endometrial endometrioid carcinoma (5), cervical adenocarcinoma (2), metastatic colon cancer (2), metastatic breast cancer (1), mesothelioma (1), uterine adenomyosis (1), endometrioma (2). The false positive and false negative rates for PAX8 alone were 21% and 0% respectively. However, when combining with Calretinin results and clinicopathological findings, the sensitivity and specificity of PAX8 for diagnosing cancer cells were both over 95%.
Conclusions: PAX8 is a sensitive and specific biomarker to detect cancer cells in pelvic washing specimen when it is combined with Calretinin staining. The most common PAX8 false positive cells are benign cells of Mullerian origin. Clinicopathological correlation is necessary in this setting.
Wednesday, March 2, 2011 1:00 PM
Poster Session VI # 76, Wednesday Afternoon