Animal model data of mitogen‐activated protein kinase kinase (MEK) inhibitor use has recently demonstrated an attenuation of leptomeningeal disease in a murine model of CMN syndrome.46 As a result we have used the MEK inhibitor trametinib as therapy in a small series of four patients with NRAS‐mutated CNS melanoma (three of whom had CMN).47 This demonstrated measurable and objective relief of symptoms and signs in all patients, although to varying degrees. The gene discussed is MAP2K7; the disease is congenital mesoblastic nephroma.