2004 WHO classification of the renal tumors of the adults.

Background: The recently introduced 2004 World Health Organisation (WHO) classification of the adult renal epithelial neoplasms is meant to replace the previous 1998 WHO classification. Methods and results: The 2004 WHO classification is based on pathology and genetic abnormalities. The description of categories has been expanded to improve their recognition and new diagnostic categories are included. Emphasis has been placed on defining familial renal cancer, carcinoma associated with Xp11 translocations, carcinoma associated with neuroblastoma, multilocular cystic renal cell carcinoma, tubular, mucinous and spindle cells carcinoma; and mixed epithelial and stromal tumour. The potentially aggressive epithelioid angiomyolipoma is recognised. Conclusions: Recognising these categories may have important implications in patients’ clinical management.