Successful grading of renal-cell carcinoma in fine-needle aspirates†

Early-stage renal-cell carcinoma is more frequently diagnosed due to more frequent use of advanced radiologic techniques. Partial nephrectomy may be curative for small tumors and may sometimes be necessary if the opposite kidney is functionally compromised. This therapeutic option is however not possible in high-grade neoplasms. In the current study, we attempted to grade cases of renal-cell carcinoma on smears obtained from preoperative fine-needle aspirates (FNA). Eighteen cases of histologically proven renal-cell carcinoma formed the basis of this study. FNAs were performed prior to nephrectomy. FNA smears were blindly reviewed, and the cases were evaluated for cellularity, nuclear to cytoplasmic (N/C) ratios, nuclear pleomorphism, and the presence of naked nuclei and prominent nucleoli; cases were graded according to the presence or absence of these criteria and their combination. The cases were cytologically graded from grade I–IV and then were given a low grade if the tumor was considered grade I or II, or high grade if the tumor was considered grade III or IV. The histology of the neoplasms was reviewed, and the tumors were graded according to the Fuhrman nuclear grading system. Correlation between the cytologic and histologic grades within the same histologic grade was seen in 13 of the 18 cases (72.2%). The difference was no more than one grade for each discrepancy. When grading as high or low grade was used, agreement was seen in 100% of the cases. The most reliable cytologic features seen on cytology distinguishing low- from high-grade tumors were the N/C ratio and the presence or absence of nucleoli. Pleomorphism, naked nuclei, and increased cellularity were less distinguishing features. We conclude that grading of renal-cell carcinoma can be reliably achieved in FNA material. Preoperative FNAs can thus be performed on small renal neoplasms with subsequent conservative treatment if the tumor proves to be low grade. Diagn. Cytopathol. 2000;22:223–226. © 2000 Wiley-Liss, Inc.