Efficacy of Sirolimus in Treating Refractory Lymphatic Malformation in Noonan Syndrome: A Case Study

A female patient with Noonan syndrome, attributed to a pathogenic <i>RIT1</i> variant, presented with white perineal discharge at 8 years and 5 months of age. She had a history of chylothorax and recurrent respiratory infections requiring hospitalization. Discharge analysis revealed 99.5% lymphocytes and elevated triglyceride levels (1939 mg/dL; 21.9 mmol/L). Magnetic resonance imaging and contrast-enhanced computed tomography identified lymphatic abnormalities extending from the thoracic to the pelvic region. We suspected that the chylous ascites was being discharged through the genitals. Administration of sirolimus, an mTOR inhibitor, was initiated, leading to a significant reduction in perineal chyle discharge and improved respiratory function with no adverse events. Sirolimus shows promise as a therapeutic intervention for lymphatic abnormalities in patients with Noonan syndrome; however, long-term follow-up is necessary to evaluate its efficacy and safety.