Abstract
Background
Grading of clear cell renal cell carcinoma now focuses on the prominence of the nucleolus; however, there may be variability in how pathologists interpret this criterion.
Methods
An online survey was distributed via email and social media to pathologists.
Results
Excluding trainees, 91 responses were received, including 77 self-identified as genitourinary (GU) and 14 non-GU. Most did not require nucleoli to be eosinophilic when determining visibility (78% GU and 71% non-GU). Most indicated that nucleoli visualized at 40× magnification at all would be considered grade 2, even if nucleoli are not eosinophilic/large (69% GU and 57% non-GU), with similar results for grade 2 versus 3 (10×) at 61% GU and 71% non-GU. For a photomicrograph at 40× magnification with visible but basophilic nucleoli, most reported grade 2 (96% GU and 79% non-GU). For an image with more prominent nucleoli described as visible at 10×, 84% of GU and 71% non-GU reported grade 3. Respondents estimated using grade 1 in 5% or less of resection specimens (76% GU, 58% non-GU). For multinucleated cells with bland individual nuclei, most (83% GU, 86% non-GU) would not consider this grade 4.
Conclusion
Although grading guidelines indicate that renal cell carcinoma nucleoli should be prominent/eosinophilic to assign grade 2 or 3, most pathologists assign the higher grade if nucleoli are visible at all. Further refinement is needed for grading cells with multiple but non-bizarre nuclei.