The 5th edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems contains relevant revisions and introduces a group of molecularly defined renal tumour subtypes. Herein we present the World Health Organization (WHO) 2022 perspectives on papillary and chromophobe renal cell carcinoma with emphasis on their evolving classification, differential diagnosis, and emerging entities. The WHO 2022 classification eliminated the type 1/2 papillary renal cell carcinoma (pRCC) subcategorization, given the recognition of frequent mixed tumour phenotypes and the existence of entities with different molecular background within the type 2 pRCC category. Additionally, emerging entities such as biphasic squamoid alveolar RCC, biphasic hyalinizing psammomatous RCC, papillary renal neoplasm with reverse polarity, and Warthin-like pRCC are included as part of the pRCC spectrum, while additional morphological and molecular data are being gathered. In addition to oncocytomas and chromophobe renal cell carcinoma (chRCC), a category of "other oncocytic tumours" with oncocytoma/chRCC-like features has been introduced, including emerging entities, most with TSC/mTOR pathway alterations (eosinophilic vacuolated tumour and so-called "low-grade" oncocytic tumour), deserving additional research. Eosinophilic solid and cystic RCC was accepted as a new and independent tumour entity. Finally, a highly reproducible and clinically relevant universal grading system for chRCC is still missing and is another niche of ongoing investigation. This review discusses these developments and highlights emerging morphological and molecular data relevant for the classification of renal cell carcinoma.
Histopathology. 2022 May 21 [Epub ahead of print]
João Lobo, Riuko Ohashi, Mahul B Amin, Daniel M Berney, Eva M Compérat, Ian A Cree, Anthony J Gill, Arndt Hartmann, Santosh Menon, George J Netto, Maria R Raspollini, Mark A Rubin, Puay Hoon Tan, Satish K Tickoo, Toyonori Tsuzuki, Samra Turajlic, Ming Zhou, John R Srigley, Holger Moch
Department of Pathology, Portuguese Oncology Institute of Porto (IPOP), R. Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal., Histopathology Core Facility, Niigata University Faculty of Medicine, Niigata, Japan., Department of Pathology and Laboratory Medicine, University of Tennessee Health Sciences Center, Memphis, USA., Centre for Molecular Oncology, Barts and the London School of Medicine and Dentistry, London, UK., Department of Pathology, Hôpital Tenon, Sorbonne University, Paris, France., International Agency for Research on Cancer (IARC), World Health Organization, Lyon, France., Sydney Medical School, The University of Sydney, Sydney, Australia., Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany., Department of Pathology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India., Department of Pathology, University of Alabama, Birmingham, Alabama, USA., Histopathology and Molecular Diagnostics, Careggi University Hospital, Florence, Italy., Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA., Division of Pathology, General Hospital, Singapore, Singapore., Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Department of Surgical Pathology, Aichi Medical University Hospital, Nagakute, Japan., Renal and Skin Units, The Royal Marsden Hospital NHS Foundation Trust, London, The Francis Crick Institute, UK, London, UK., Department of Pathology, Tufts Medical Center, Boston, MA, USA., Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada., Department of Pathology and Molecular Pathology, University and University Hospital Zurich, Zurich, Switzerland.