Ultrastructural morphometry of nucleoli: Potential usefulness for objective grading of clear cell renal cell carcinoma

The authors attempted to determine the potential prognostic value of severa l ultrastructural morphometric parameters, including nuclear, nucleolar, an d cytoplasmic features, that could be used in the objective and reproducibl e histological grading of clear cell renal cell carcinoma. Several nuclear and cytoplasmic parameters were assessed by ultrastructural morphometry in 26 consecutive cases of clear cell renal cell carcinoma. The nuclear and nu cleolar sizes, the number of nucleoli per nuclear section and the number of marginated nucleoli, Fuhrman's nuclear grade, and Robson's stage were reco rded. in addition, the proportion of cytoplasmic components was semiquantit atively estimated and compared to light microscopic appearance. Follow-up r anged from 5 to 15 years (mean = 10 years). Statistical evaluations were pe rformed by means of the Pearson or Spearman correlation coefficient tests, and differences in survival were estimated, using the Mantel-Cox proportion al risk method. Differences in survival among patients with a mean nuclear area over and under 160 mum(2), and among those with a mean nucleolar area over and under 10 mum(2), were statistically significant. (Cutoff points we re selected at the median value for both parameters; Mantel-Cox test: chi ( 2) = 7.102, p < .01; and <chi>(2) =11.096, p < .001, respectively). Fuhrman 's nuclear grade (p < .01) and tumor stage at diagnosis (p < .001) were als o related to survival. These data suggest that, out of all the ultrastructu ral morphometric features, nucleolar area is the most useful in the reprodu cible and accurate grading of clear cell renal cell carcinoma.