LOT and HOT … or not. The proliferation of clinically insignificant and poorly characterised types of renal neoplasia.

The classification of malignant tumours is influenced by both immunohistochemical and molecular genetic findings. This is highlighted in the latest World Health Organization classification of renal neoplasia, which has a tumour category of 'tumours that are molecularly defined'. This implies that the defining molecular features are integral to tumourigenesis, which may not necessarily be the case.