[827] Expression of Parafibromin in Renal Tumors and Its Potential Correlation with Tumor Prognosis

Chunhua Cui, Priti Lal, Yuxiang Ma, John E Tomaszewski, Zhanyong Bing. Hospital of the University of Pennsylvania, Philadelphia, PA

Background: Parafibromin, encoded by HRPT2 gene, is a recently identified tumor suppressor. Complete and partial loss of parafibromin expression has been found in the parathyroid carcinoma, the hyperparathyroidism-jaw tumor (HPT-JT), lung carcinoma and breast carcinoma. So far, little has been known about its role in renal tumors. Parafibromin expression has only been examined in a small series of chromphobe renal cell carcinomas and oncocytomas of kidney. In this study, we report the expression of parafibromin in a large series of renal tumors, including clear cell renal cell carcinoma (RCC), papillary RCC, chromophobe RCC and oncocytoma, using tissue microarrays (TMA).
Design: 19 cases of renal oncocytoma, 23 cases of chromophobe RCC, 37 cases of papillary RCC, and 61 cases of clear cell RCC, from 1991 to 2009, were retrieved from the pathology archives of the Hospital of the University of Pennsylvania and used for the construction of multiple renal tumor TMAs. The constructed renal tumor TMAs were sectioned, incubated with primary and secondary antibodies and visualized with the avidin-biotin-peroxidase complex method. The staining was classified into 3 patterns according to Gill et al. Diffuse staining in over 95% nuclei with strong intensity was considered "diffusely strong positive." No nuclear staining in all (>99%) of tumor tissue was defined as "Negative staining". All other staining patterns were "Weak staining".
Results: All of the 19 cases of oncocytoma showed strong nuclear staining (100%). 12 of the 23 chromophobe RCC showed positive nuclear staining (52%); 11 were negative. Among the 37 cases of papillary RCC, 15 are type 1 papillary RCC, 1 of them was positive for parafibromin stain; 22 are type 2 papillary RCC, 6 of them are positive for parafibromin stain; the overall positive cases are 7 (19%). Out of the 61 clear cell RCC cases, only 3 of them were positive for parafibromin stain (5%).
Conclusions: Parafibromin expression varies significantly among the different types of renal tumors. Parafibromin may be a helpful marker in the differential diagnosis of renal tumors. Similar to parathyroid carcinomas, parafibromin appears to have tumor suppressor functions in renal carcinomas. Preserved expression of parafibromin is associated with benign tumors in the spectrum- oncocytoma; whereas loss of its expression is associated with malignant tumors bearing more adverse prognosis. These findings may indicate a potential role of parafibromin as a prognostic marker in renal tumors.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 150, Monday Morning


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