PAX8 is expressed in the majority of renal epithelial neoplasms: an immunohistochemical study of 223 cases using a mouse monoclonal antibody

Aims: PAX8 is a cell lineage-specific transcription factor which plays a crucial role in the organogenesis of the kidney, thyroid gland and Müllerian duct. A previous study showed that PAX8 is a specific and sensitive marker for both renal and ovarian carcinomas. The purpose of this study is to investigate PAX8 expression using a new monoclonal PAX8 antibody in a larger number of renal epithelial neoplasms including clear cell renal cell carcinoma, papillary renal cell carcinoma, chromophobe renal cell carcinoma and renal oncocytoma. Methods: PAX8 immunohistochemical staining was performed on tissue microarrays containing 84 cases of clear cell renal cell carcinoma, 66 cases of chromophobe renal cell carcinoma, 57 cases of papillary renal cell carcinoma and 16 cases of renal oncocytoma. Results: PAX8 expression was detected in 93% (78/84) of cases of clear cell renal cell carcinoma, 80% (53/66) of cases of chromophobe renal cell carcinoma, 95% (54/57) of cases of papillary renal cell carcinoma and 94% (15/16) of cases of renal oncocytoma. Conclusions: PAX8 is expressed in the majority of renal epithelial neoplasms including renal cell carcinomas and oncocytomas and the monoclonal PAX8 antibody is more sensitive than polyclonal antibody to detect chromophobe renal cell carcinoma. These results showed that PAX8 is a valuable marker for nephric neoplasms