What is the WHO updated classification of renal cell tumors?

Updated: May 20, 2019
  • Author: Kush Sachdeva, MD; Chief Editor: E Jason Abel, MD  more...
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Answer

In 2016, the World Health Organization released an updated classification of renal cell tumors that expanded the subtypes of renal cell carcinoma (RCC) based on tumor histology, chromosomal alterations, and molecular pathways. The update included the following five newly recognized epithelial renal tumors [74] :

  • Hereditary leiomyomatosis and renal cell carcinoma (RCC) syndrome–associated RCC
  • Succinate dehydrogenase–deficient RCC
  • Tubulocystic RCC
  • Acquired cystic disease–associated RCC
  • Clear cell papillary RCC

Other revisions to RCC classification included the following [74] :

  • Clear cell RCC is characterized in >80% of sporadic cases by VHL gene mutations, hypermethylation of VHL gene promoter, and loss of heterozygosity

  • Multilocular cystic clear cell RCC has been renamed as multilocular cystic renal neoplasia of low malignant potential due to its indolent behavior.

  • Papillary renal cell carcinomas are histologically and cytogenetically defined by two main subtypes, type 1 and type 2, but they represent a heterogeneous disease that includes both indolent and agressive tumors. RCCs associated with hereditary leiomyomatosis are usually type 2 papillary RCC and have a poor prognosis with a high risk of dissemination.
  • The oncocytic variant of papillary RCC should be reclassified as type 1 (mainly) or type 2 papillary RCC.

  • The maximum size of papillary adenoma was 5 mm but is now ≤15 mm in its largest dimension.

  • The main prognostic factors in chromophobe RCC are tumor stage, the presence of necrosis, a sarcomatoid and/or rhabdoid component, and small vessel invasion.

  • The diagnosis of the highly aggressive collecting duct carcinoma is based on six histological features: medullary location, infiltrative growth pattern, tubular architecture, desmoplastic stromal reaction, high-grade atypia, and that the tumor is neither an RCC nor a transitional cell carcinoma.


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