Thoracic Duct Embolization in a Case of Congenital Chylothorax

Chylothorax, characterized by the accumulation of lymph in the pleural space due to leakage from thoracic lymphatic vessels, is the most common type of pleural effusion in neonates [1]. Patients typically present with respiratory distress and are diagnosed through pleural fluid analysis. The presence of pleural fluid with leukocytes > 1000/µL, lymphocytes > 70%−80%, and triglycerides > 110 mg/dL in patients receiving enteral feeding is considered indicative of chylothorax [1]. Chylothorax is categorized into three distinct classifications: congenital, traumatic, and non-traumatic. Significant pleural fluid loss, ventilation difficulties, the need for pleural drainage, and total parenteral nutrition (TPN) increase the risk of infectious and metabolic complications [2]. Although various medical and surgical treatment options are available, such as octreotide infusion, propranolol, sirolimus, pleurodesis, or thoracic duct ligation, prolonged conservative treatments have been associated with increased morbidity and mortality [1, 2]. In this case report, we present our experience with thoracic duct embolization (TDE)—a technique with very limited experience in pediatric patients—in our patient diagnosed with congenital chylothorax who did not respond to conservative treatment. A 23-day-old male infant presented to the emergency department with respiratory distress, cough, and irritability. Antenatal follow-up was unremarkable, and the baby was born via cesarean section at 38 weeks of gestation weighing 2715 g. Decreased breath sounds were noted at the right lung base. Chest X-ray revealed increased opacity in the right lower zone, and thoracic ultrasound (USG) showed massive right-sided effusion (see Figure 1A). The patient was placed under hood oxygen therapy. A right-sided chest tube was inserted, and pleural fluid analysis revealed triglyceride levels of 6785 mg/dL and a leukocyte count of 60,000/mm³. Oral feeding was discontinued, and TPN, along with octreotide infusion, was initiated due to chylous effusion. Echocardiography revealed only a patent foramen ovale. Thoracic MRI showed no evidence of mass lesion, azygos-hemiazygos duct dilation, lymphatic malformation, sequestration, or vascular anomaly. Congenital infections (toxoplasmosis, rubella, cytomegalovirus, syphilis, varicella-zoster, herpes infections, and parvovirus B19) were ruled out. Genetic analysis was performed to exclude syndromic associations, and no abnormalities were detected. As the color of the pleural drainage lightened, feeding was initiated with a medium-chain triglyceride (MCT)-rich formula, but the recurrence of chylous effusion led to the addition of propranolol to the octreotide therapy. The patient was monitored with high-flow nasal cannula oxygen (HFNCO) due to the presence of high-level effusion and respiratory distress. The monitoring period continued for a duration of 10 days. Intravenous immunoglobulin (IVIg) supplementation was administered for secondary immunodeficiency due to low serum immunoglobulin G levels, and albumin infusion was administered twice. At 40 days of age, the chest tube was removed after a reduction in drainage, and enteral feeding with MCT formula was gradually increased. On the 84th day postnatal, fever, restlessness, and tachypnea were detected, and intravenous piperacillin-tazobactam was initiated for nosocomial infection. SARS-CoV-2 (Covid-19) was detected in the tests, and the antibiotic therapy was completed within 14 days. In view of the patient's persistent pleural effusion, the octreotide infusion was increased to 10 mcg/kg/h (see Figure 1B). Nevertheless, in consideration of the patient's inability to tolerate increased oral feeding and the persistence of the pleural effusion, on the 122nd day after birth, TDE was performed by injecting Lipiodol (an opaque substance containing a mixture of iodinated ethyl esters of fatty acids used in radiological imaging) into the inguinal lymph nodes via percutaneous access under ultrasound guidance by interventional radiology. It was predicted that the embolization agent would reach the thoracic duct within 12 h; therefore, an abdominal X-ray was scheduled for the 24th hour and a thoracic ultrasound for 72 h later. Subsequent follow-up imaging following embolization revealed a substantial reduction in pleural effusion, as evidenced by thoracic ultrasound and chest X-ray (see Figure 2A–C). Enteral feeding was increased and TPN was discontinued on Day 131; octreotide was stopped on Day 153. The patient was discharged on Day 155 with complete resolution of the effusion. At 7 months, the MCT formula was switched to the regular formula with no recurrence, and at 15 months, growth and development remain age-appropriate. Congenital chylothorax is a rare but the most common cause of neonatal pleural effusion, occurring in approximately 1 in 10,000 to 15,000 pregnancies [3]. It often results from lymphatic vessel anomalies or thoracic cavity defects. It is more frequent in males and typically affects the right pleural space due to lymphatic anatomy. Antenatal chylothorax can impair lung growth and development, potentially leading to pulmonary hypoplasia, pulmonary hypertension, decreased venous return, heart failure, hydrops, and fetal mortality [1]. It may be associated with syndromes such as Noonan, Turner, Down, Ehlers−Danlos, and Costello, as well as TORCH infections [4]. Due to the presence of lymphocytes, antibodies, complement proteins, coagulation factors, immunoglobulins, nutrients, and fluids in chylous effusion, patients are at high risk for malnutrition, dehydration, infection, and bleeding, necessitating close monitoring. Reported mortality rates range from 30% to 70%, particularly in severe cases and in the presence of associated complications [4]. The goal of chylothorax treatment is to reduce effusion and allow time for damaged lymphatic vessels to heal and mature. Supportive management, including respiratory support, pleural drainage, cardiovascular stabilization, nutritional management, pharmacologic reduction of intestinal chyle production, and pain control, is crucial. TPN administration until lymphatic drainage decreases below 2 mL/kg/day, followed by enteral feeding with MCT formula, albumin supplementation for hypoalbuminemia, octreotide infusion to reduce chyle output, propranolol or sildenafil for lymphatic malformations, and sirolimus for lymphangiomatosis are among the recommended options [1]. In our patient, TPN and octreotide were initially started. Enteral feeding was introduced once effusion decreased, but due to persistent drainage, propranolol was added. Clinical improvement was not observed during concomitant COVID-19 infection. TDE may be considered as an option in refractory cases after failure of conservative therapy, since long-term conservative treatments have been shown to increase the risk of infectious and metabolic complications [1, 5]. In the review by Rocha et al., who developed algorithms for congenital and traumatic chylothorax, an invasive approach is recommended in cases where, following 1 week of conservative treatment, there is drainage of > 10 mL/kg/day or > 100 mL/day for 5 consecutive days, or in cases of uncontrollable serious metabolic and nutritional complications [1]. Surgical options include thoracic duct ligation, pleurodesis, TDE, pleuroperitoneal shunt, or diaphragmatic fenestration. Al-Tawil et al. recommended invasive treatment after 4–5 weeks of unsuccessful conservative therapy [5]. Despite the implementation of all available conservative treatment options for the patient, these proved unsuccessful. Consequently, after prolonged failure of all available conservative treatment options and careful multidisciplinary evaluation, the decision was made to proceed with an invasive approach 15 weeks after diagnosis. In the literature, Lipiodol (poppy seed oil) injection, which produces an inflammatory process and occludes the chyle leak, has been reported to be successful in a former 35-week male infant with refractory chylothorax [1]. TDE, a minimally invasive percutaneous procedure performed by interventional radiologists, may resolve chylous leakage. Two main lymphangiography techniques exist. The first of these involves the use of embolization agents for repair via bilateral pedal lymphangiography and transabdominal catheterization of the pedal lymphatic vessels, the cisterna chyli, or thoracic duct. The second is a more recent technique that has yielded promising results in a shorter time via inguinal intranodal lymphangiography with the aid of ultrasound [6, 7]. Contraindications to lymphangiography include the presence of a right-to-left cardiac shunt and severe lung disease [1]. In non-traumatic chylothorax, initial success rates of up to 73.8% have been reported, although overall success is lower than in traumatic cases, mainly due to technical difficulties accessing the thoracic duct or inadequate opacification of the retroperitoneal lymphatic system [7]. Reported acute complication rates are 2%–6%, typically self-limited. Long-term complications occur in up to 14% of patients and may include leg edema, abdominal distension, or chronic diarrhea [8]. No short- or medium-term side effects were observed during follow-up in our patient who underwent the new intranodal technique. However, a longer follow-up is required to assess potential late complications. The reason we have not seen side effects such as lymphedema or chronic digestive changes, which are possible late complications, in the first year after TDE, is that our follow-up period is still short. However, due to the minimal amount of Lipiodol required to repair damaged lymphatic vessels in infants, and the fact that children's vessel diameters increase as they grow, these late complications may be less frequent in children; however, this remains speculative and requires long-term follow-up. We believe that TDE may represent a viable therapeutic option in selected infants with refractory chylothorax. However, given the technical complexity and risks involved, we believe that this procedure should only be performed at centers with experience in pediatric interventional radiology. More extensive studies and long-term follow-up are required for TDE to be accepted as standard in pediatrics. Lymphangiography and TDE may represent a minimally invasive alternative to surgical approaches in selected cases. Although rare pediatric cases have been reported to date, success rates in adults are encouraging. The TDE procedure has emerged as a potentially viable minimally invasive intervention for infants diagnosed with congenital chylothorax who have demonstrated an unresponsiveness to conservative treatment modalities. However, given the limitations of a single case report, further research is required in the form of larger pediatric series and long-term follow-up studies before this technique can be recommended more broadly. Esin Gizem Olgun: conceptualization, investigation, methodology, writing – original draft, validation, visualization, writing – review and editing. Seyhan Çelik Merteşe: resources, data curation. Arzu Meltem Demir: formal analysis, resources, funding acquisition. Secahattin Bayav: data curation, software. Serpil Özdemir: funding acquisition. Mukaddes Ağırtıcı: data curation, resources. Zarife Kuloğlu: supervision, visualization. Semra Küçük Öztürk: validation, funding acquisition. Ceyda Tuna Kırsaçlıoğlu: supervision, visualization. Aydan Kansu: writing – review and editing, project administration. Sadık Bilgiç: supervision, Visualization. Nazan Çobanoğlu: project administration, writing – review and editing, supervision. The authors received no specific funding for this work. IRB review was waived per institutional policy (Ethics Committee of the Ankara University Faculty of Medicine, Ankara, Turkey). This report does not require the approval of an ethics committee. Written consent has been obtained from the family. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.