CSY Chan, STY Lui, APY Liu, ACC Fu

Abstract

Noonan syndrome is an autosomal dominant genetic disorder which causes malformation of the lymphatic system, leading to lymphangiectasia of the intestines and protein-losing enteropathy. We report a case of a 15-year-old Chinese girl with PTPN11-mutation Noonan syndrome with recurrent lower limb oedema and hypoalbuminaemia. Multiple targeted investigations confirmed the diagnosis of lymphangiectasia leading to protein-losing enteropathy, including a Tc99m human serum albumin, an oesophageoduodenoscopy with biopsy, and magnetic resonance lymphangiogram showing features of central conducting lymphatic anomaly with abnormal lymphatic flow. Being refractory to conventional treatment strategies, initiation of Sirolimus, an m-TOR inhibitor, yielded satisfactory clinical improvement in this patient. This case demonstrated the diagnostic complexity and management challenge in patients with protein-losing enteropathy caused by lymphangiectasia, which is one of the rare complications in Noonan syndrome. Early commencement of Sirolimus with close monitoring of side effects is helpful in disease control and symptom resolution.