Nontraumatic Chylothorax in the Setting of Superior Vena Cava Stenosis

IntroductionChylothorax is a rare but potentially morbid complication following thoracic surgery. Nontraumatic chylothorax is even less common and typically is due to malignancy, congenital or idiopathic disorders of the lymphatic system, systemic diseases, and infection [1]. Here, the authors present a case of nontraumatic chylothorax due to central venous stenosis.Case PresentationA 57-year-old man with a history of renal failure and previous renal transplantation complicated by rejection requiring dialysis presented to the emergency room with the acute onset of dyspnea, nonproductive cough, and an inability to lay flat. He had a history of prior left tunneled internal jugular dialysis catheter placement and left upper extremity dialysis fistula, which had previously required multiple fistulagrams for prolonged bleeding and elevated venous pressures. During examination, his chest x-ray showed a large left pleural effusion and he underwent thoracentesis by the emergency medicine team with evacuation of 2 L of turbid fluid.Given his chronic immunosuppression, he was admitted by internal medicine for initiation of intravenous (IV) antibiotics. Thoracic surgery, transplant infectious disease, and nephrology were consulted following admission. He underwent an echocardiogram, which did not demonstrate congestive heart failure. A computed tomography (CT) scan demonstrated right internal jugular occlusion, superior vena cava (SVC) stenosis, prominent thoracic venous collaterals, and cervical and mediastinal lymphadenopathy (Figures 1 and 2). His pleural fluid cytology and cultures were negative, but testing indicated the presence of chylomicrons and his triglyceride level was 1154 mg/dL, which was consistent with a chylothorax.His IV antibiotics were discontinued, and he was placed on a medium chain triglyceride diet with octreotide three times daily. A cervical lymph node biopsy was negative for lymphoma, and he was monitored closely as an outpatient for recurrence. He continued to reaccumulate chylous fluid despite dietary modifications and required additional thoracenteses.Subsequently, the decision was made to proceed with a venogram and possible SVC stent placement. If this were unsuccessful, he would undergo thoracoscopic thoracic duct ligation. He was found to have hemodynamically significant stenosis of the superior SVC resulting in a 21 mm Hg pressure gradient between the left innominate vein and central SVC. He underwent successful stent placement with decompression of previously visualized left thoracic venous collaterals (Figure 3). After stent placement the pressure gradient was reduced to 1 mm Hg. The patient subsequently has remained stable, with resolution of his chylothorax without the need for further interventions.Learn more: https://www.ctsnet.org/article/nontraumatic-chylothorax-setting-superior-vena-cava-stenosis

引言
乳糜胸（chylothorax）是胸部手术后罕见但可引发严重不良预后的并发症。非创伤性乳糜胸更为少见，其病因多为恶性肿瘤、先天性或特发性淋巴系统疾病、全身性疾病及感染[1]。本文报告1例由中心静脉狭窄（central venous stenosis）所致的非创伤性乳糜胸。

病例介绍
患者为57岁男性，有肾衰竭病史，既往肾移植术后并发排斥反应，需维持透析治疗。患者因急性起病的呼吸困难、干咳、无法平卧就诊于急诊。既往曾留置左侧隧道式颈内静脉透析导管，并建立左上肢透析动静脉瘘，此前因出血不止及静脉压升高，多次行瘘管造影术。
查体期间胸部X线提示左侧大量胸腔积液，急诊内科团队为其行胸腔穿刺术，引流出2 L浑浊液体。
鉴于患者长期免疫抑制状态，收入内科病房启动静脉抗菌药物治疗。入院后请胸外科、移植感染科及肾内科会诊。
患者行超声心动图检查，未发现充血性心力衰竭。计算机断层扫描（CT）提示右侧颈内静脉闭塞、上腔静脉（SVC）狭窄、胸壁静脉侧支循环显著扩张，以及颈部及纵隔淋巴结肿大（图1、图2）。
胸腔积液细胞学检查及培养结果均为阴性，但检测提示存在乳糜微粒，甘油三酯水平达1154 mg/dL，符合乳糜胸诊断。
遂停用静脉抗菌药物，予中链甘油三酯饮食联合奥曲肽（octreotide）每日三次治疗。颈部淋巴结活检排除淋巴瘤，患者作为门诊患者接受密切随访以监测复发。尽管调整饮食，患者胸腔乳糜液仍持续积聚，需再次行胸腔穿刺术。
随后决定行静脉造影（venogram）术并视情况行上腔静脉支架置入术；若该治疗无效，则行胸腔镜下胸导管结扎术。
术中发现上腔静脉存在具有血流动力学意义的狭窄，左无名静脉与上腔静脉中心段之间的压力梯度达21 mmHg。成功行支架置入术，此前可见的胸壁左侧静脉侧支循环得以减压（图3）。支架置入后压力梯度降至1 mmHg。患者后续病情稳定，乳糜胸得以缓解，无需进一步干预。

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