NRAS and congenital mesoblastic nephroma: Patients with multiple CMN also have an increased risk of primary melanoma developing in the CNS or in the skin.1 The underlying cause of multiple CMN and so‐called NCM was recently found to be mosaicism for heterozygous activating mutations in codon 61 of NRAS, a developmental gene and oncogene involved in the control of key cell signalling pathways.2 However, the onset of melanoma requires further genetic events.2