WHO 2022 Renal Cell Tumor Classification: Imaging Features and Clinical Implications.

The World Health Organization classification of renal cell tumors was updated to its fifth edition in 2022 and incorporated significant changes with contributions from pathologists and radiologists. In the 2022 updated classification, epithelial renal tumors are now divided into six categories. Four of these six categories represent the major subtypes of renal tumors: clear cell renal tumors, papillary renal tumors, oncocytic and chromophobe renal tumors, and collecting duct tumors. Two additional categories, representing relatively rare renal tumors, termed other renal tumors and molecularly defined renal carcinomas, have been introduced. While neoplasms in the other renal tumors category are classified on the basis of their histopathologic features, similar to the major subtypes, molecularly defined renal carcinomas represent a new category based on molecular characteristics. In recent years, the number of these rare subtypes has increased significantly. Many of these relatively rare renal tumors represent conventional subtypes that have been reclassified or renamed. Notably, papillary renal cell carcinoma (pRCC) type 2 has been reclassified as other renal tumors or molecularly defined renal carcinomas. As a result, many tumors in these two categories demonstrate gradual enhancement, similar to the enhancement of pRCCs. However, one or more of the following features may differ from those of typical pRCCs: patient age, growth pattern, nonenhanced attenuation at CT, degree of enhancement, homogeneity, T2 signal intensity, and presence of metastases. Careful evaluation of these features can raise suspicion for a rare subtype and is essential for guiding urologists in determining the surgical strategies and guiding pathologists in selecting appropriate immunohistopathologic and/or genetic tests for accurate diagnosis. ©RSNA, 2026 Supplemental material is available for this article. See the invited commentary by Davenport and Pedrosa in this issue.