[810] Fuhrman Grading in Renal Cell Carcinoma: Comparison between Core Needle Biopsies and Surgical Resections

Jennifer A Bennett, Lee A Wilkinson, Catherine S Abendroth, Elizabeth E Frauenhoffer, Bing Han. Penn State Hershey Medical Center, Hershey, PA

Background: With increased use of computed tomography (CT) imaging, many renal cell carcinomas are being detected incidentally. Fine needle aspiration (FNA) is often used for confirmation of the diagnosis. Recently, surgeons have requested Fuhrman grading of the lesion, resulting in a core needle biopsy being performed simultaneously with FNA. We undertook a study to determine whether Fuhrman grading of biopsies correlates with that of the nephrectomy specimen.
Design: The pathology database was searched for patients who had both a biopsy and nephrectomy performed. The cases were randomly blinded and reviewed by three staff pathologists. Biopsies and nephrectomies were scored according to standardized Fuhrman grading criteria. The results were tabulated to determine whether Fuhrman grading of biopsy correlated with that of the nephrectomy.
Results: The average Fuhrman grade ranged from 1.00-2.67 for the biopsies and from 1.33-3.67 for the nephrectomies. In general, the biopsy underestimated the Fuhrman grade when compared to the nephrectomy by approximately one grade. In 4/19 cases the Fuhrman grade was higher in the biopsy than in the nephrectomy. There was interobserver agreement in 6/19 cases (kappa = 0.578) for both biopsies and nephrectomies. Comparison between the average Fuhrman grades for biopsies versus nephrectomies resulted in a p-value of 0.004. Reclassification of the Fuhrman grade into low grade (1-2) versus high grade (3-4) showed agreement in 14/19 cases (kappa = 0.825) for biopsies and 12/19 cases (kappa = 0.754) for nephrectomies. Comparison of biopsies versus nephrectomies in the two-tiered scoring system resulted in a p-value of 0.083.
Conclusions: This study illustrates the degree of interobserver variability present when using the traditional Fuhrman grading system. When using the two-tiered system, interobserver variability is improved. The likelihood of an increase in the Fuhrman grade from biopsy to nephrectomy is common, but less so when utilizing the two-tiered system. The clinical utility of a prenephrectomy biopsy is highest when attempting to provide basic diagnostic information. Interpreting Fuhrman grade on limited material is clearly fraught with limitations; however, with the advent of less invasive surgical approaches including radioablation and partial nephrectomy, the biopsy grade may play an increased role in refining clinical management. From the evidence gathered here, both interobserver variability and biopsy to surgical consistency is improved when utilizing the two-tiered grading system.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 156, Wednesday Afternoon

 

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