How should renal cell carcinoma be graded using the World Health Organization (WHO)/International Society of Urological Pathology (ISUP) grading system?   A recent publication in Histopathology @Histo_Journal by Drs. @GladellPaner @DrMahul , Jung Woo Kwon, and Holger Moch provides a comprehensive and timely review of this important topic.   The review summarizes the validation, practical application, and ongoing controversies surrounding the WHO/ISUP grading system for clear cell and papillary renal cell carcinoma. Key topics include intratumoral grade heterogeneity, interpretation of multinucleated cells, spindle cell and sarcomatoid differentiation, rhabdoid change, grading in needle biopsies and multifocal tumors, and challenges specific to papillary renal cell carcinoma. We also examine emerging evidence supporting the prognostic value of reporting the extent of sarcomatoid differentiation and high-grade components while highlighting areas that require further validation.   In addition, the review explores innovative grading strategies, including incorporation of tumor necrosis into grading and novel architecture- and pattern-based risk assessment models, which may further improve prognostic stratification beyond the current WHO/ISUP system. Importantly, the authors provide practical guidance for surgical pathologists while identifying key knowledge gaps that will help shape future research and further refine renal tumor grading.   Full article: onlinelibrary.wiley.com/doi/…   PubMed: pubmed.ncbi.nlm.nih.gov/4221…