新生儿乳糜胸是新生儿先天性胸腔积液的常见病因，常由多种原因导致胸导管及其分支淋巴管破裂，乳糜液在胸腔内蓄积所致。恶性肿瘤所致新生儿乳糜胸极为罕见。该例为国内首例新生儿纵隔神经母细胞瘤合并乳糜胸。男性患儿宫内即发现左侧胸腔积液，出生时窒息，生后以呼吸困难、全身发绀为主要表现。根据胸腔积液常规和生化诊断为左侧乳糜胸。该患儿经过持续胸腔穿刺置管引流、对症支持等多种治疗，左侧胸腔引流量达90~180?mL/d，考虑为新生儿难治性乳糜胸。生后13?d复查胸片提示左上肺野病灶，胸部CT平扫增强提示后纵隔神经母细胞瘤可能。尸检证实为后纵隔巨大神经母细胞瘤（低分化型），侵犯C₇~T₆椎管及附近竖脊肌，肝脏及双侧肾上腺有少量肿瘤组织。考虑纵隔肿瘤为乳糜胸的根本病因。

Neonatal chylothorax is a common cause of neonatal congenital pleural effusion and is often caused by the accumulation of chylous fluid in the thoracic cavity due to the rupture of the thoracic duct and its branched lymphatic vessels for a variety of reasons. Neonatal chylothorax caused by malignant tumors is extremely rare, and this is the first case of neonatal mediastinal neuroblastoma with chylothorax in China. The boy was found to have pleural effusion in the left thoracic cavity in the uterus, and experienced apnea at birth, as well as dyspnea and cyanosis as the main manifestations after birth. He was diagnosed with left chylothorax based on conventional biochemical analysis of pleural effusion. After the treatment including persistent chest drainage and symptomatic and supportive treatment, the drainage of the left thoracic cavity reached a volume of 90-180 mL per day. Neonatal refractory chylothorax was considered. Chest radiograph on day 13 after birth showed lesions in the upper left lung field, and contrast-enhanced plain CT scan of the chest suggested the possibility of posterior mediastinal neuroblastoma. The autopsy confirmed giant posterior mediastinal neuroblastoma (poorly differentiated), which involved the C₇-T₆ spinal canal and the nearby erector spinae, with a small amount of tumor tissue in the liver and both adrenal glands. Mediastinal tumor is considered the underlying cause of chylothorax in this case.