RESUMEN
Background: Refractory chylous effusions due to lymphatic dysplasia related to Noonan syndrome cause significant morbidity and mortality due to protein and immunoglobulin losses. Very few cases have been published reporting successful treatment of patients with trametinib where all conventional treatments had failed. Case summary: We present a girl with Noonan syndrome and hypertrophic cardiomyopathy who presented with life-threatening refractory chylothorax where all conventional treatment options failed. She was successfully treated with mitogen-activated extracellular signal-regulated kinase inhibitor trametinib. Discussion: MEK inhibition with trametinib is emerging as a possible salvage treatment option for a subset of patients with Noonan syndrome and severe pulmonary lymphangiectasia. More experience is required to establish optimal treatment regimen and long-term outcomes.