PAX8 [PAX8/1491&1492]

PAX8 is expressed in the thyroid (and associated carcinomas), non-ciliated mucosal cells of the fallopian tubes and simple ovarian inclusion cysts, but not normal ovarian surface epithelial cells. PAX8 is expressed in a high percentage of ovarian serous, endometrioid, and clear cell carcinomas, but only rarely in primary ovarian mucinous adenocarcinomas. Studies have also found PAX8 experession in renal tubules as well as renal carcinoma, nephroblastoma and seminoma. Over 98% of clear cell RCCs, 90% of papillary RCCs, and 95% of oncocytomas were positive for PAX8, frequencies which are similar or better than for PAX2. Similarly, the absence of expression of PAX8 in breast and other non-GYN carcinomas other than those primary to the thyroid indicates that PAX-8 is an important new marker of ovarian cancer and a useful marker for the differential diagnoses in lung and neck tumors, or tumors at distant sites where primary lung carcinoma or thyroid carcinoma are possibilities. PAX-8, combined with organ system-specific markers such as uroplakin, mammaglobin, and TTF-1 can be a very useful panel to determine the primary site of invasive micropapillary carcinomas of ovary from bladder, lung, and breast. Unlike the polyclonal anti-PAX-8 antibody, this rabbit monoclonal antibody does not react with pancreatic neuroendocrine tumors and thymic tumors.