Three Cases of Chylothorax After Lung Cancer Surgery: Possible Lymphatic Vessel Variation in the Upper Right Mediastinum

ABSTRACT

Postoperative chylothorax is an uncommon complication after lung cancer resection. However, chylous leakage caused by iatrogenic injury of aberrant mediastinal lymphatic vessels often presents massive drainage and fails conservative treatment, requiring reoperation. A retrospective analysis was performed on three patients who underwent reoperation for refractory massive chylothorax after radical resection of right upper lobe lung cancer between October 2022 and November 2023 in our center. Intraoperatively, chylous fistulas were consistently detected at the junction of the upper margin of the azygos arch and the anterolateral trachea in the right superior mediastinum. An aberrant lymphatic tubular structure was directly visualized at this anatomical site during one primary operation. Preventive suturing may be considered at this anatomical junction during extensive right superior mediastinal lymphadenectomy to prevent postoperative chylothorax.

Key Clinical Message.

These variant lymphatic vessels are typically located in the upper right mediastinum, at the intersection of the upper edge of the azygos arch and the anterolateral side of the trachea. Therefore, preventive suturing may be considered at this intersection to minimize the risk of postoperative chylothorax.

1. Introduction

Significant chylothorax following lung cancer surgery is relatively uncommon, with most cases associated with lymph node dissection [1]. Typically, the chyle volume is small, and the condition can be resolved through conservative treatments such as a low‐fat diet, total parenteral nutrition, promotion of thoracic adhesions, and the use of octreotide to facilitate fistula healing. However, damage to variant thoracic ducts or their branches during lymph node dissection frequently results in substantial chylothorax, which is difficult to treat conservatively and requires surgical intervention [2, 3]. Here, we report three cases of postoperative chylothorax caused by suspected lymphatic vessel variations in the upper right mediastinum following lung cancer surgery, along with a review of the relevant literature.

2. Case History and Examinations

From October 2022 to November 2023, three patients operated under the supervision of the same attending surgeon of our department underwent secondary surgery due to significant chylothorax after surgery. Of the three patients, two were male and one was female, with an average age of 65 years.

All nodules were peripheral. Pulmonary nodules were detected by non‐contrast chest CT during routine health check‐ups. PET‐CT was not performed given its high cost without local medical insurance reimbursement. Preoperative CT‐guided or bronchoscopic biopsy was not performed, as these imaging findings were highly suspicious for Stage‐I lung malignancy, for which primary surgical resection is the preferred strategy according to NCCN guidelines.

All patients underwent standardized preoperative evaluations, including pulmonary function, cardiac function, contrast‐enhanced brain MRI, whole‐body bone scan, and contrast‐enhanced chest and abdominal CT, to exclude distant metastasis and confirm surgical tolerance.

3. Differential Diagnosis and Treatment

The nature of pulmonary nodules in the three patients remained undetermined, with high suspicion of malignancy. Differential diagnoses included pulmonary tuberculosis, inflammatory pulmonary nodules, and benign lung tumors; definitive diagnosis relied on postoperative pathological examination.

After thorough preoperative evaluation and preparation, all three patients underwent VATS surgery. Two patients underwent VATS right upper lobectomy with systematic lymph node dissection, and one patient underwent right upper lobe posterior segmentectomy with systematic lymph node dissection. Postoperative pathological results confirmed lung adenocarcinoma in all three patients, with one patient showing mediastinal lymph node metastasis. Postoperative staging revealed one patient at pT1bN0Mx, Stage IA2 (Case 1), one patient at pT1cN0Mx, Stage IA3 (Case 2), and another patient at pT2bN2Mx, Stage IIIA (Case 3) (Table 1).

TABLE 1.

General information of the three patients.

Date of operation	Case	Gender	Age (years)	Operation (VATS)	Postoperative pathology	Postoperative pathological staging	The drainage volume of the first day after surgery	The time of conservative treatment
October 12, 2022	1	Male	58	Right upper lobe posterior segmentectomy	Adenocarcinoma	pT1bN0Mx IA2	1800 mL	2 weeks
May 10, 2023	2	Female	71	Right upper lobectomy	Adenocarcinoma	pT1cN0Mx IA3	1000 mL	2 weeks
November 20, 2023	3	Male	67	Right upper lobectomy	Adenocarcinoma	pT2bN2Mx IIIA	700 mL	1 week

4. Results, Outcome and Follow‐Up

The surgeries proceeded smoothly; however, on the first postoperative day, a large volume of milky‐white fluid was drained through the chest drainage tube (1800 mL in Case 1, 1000 mL in Case 2, 700 mL in Case 3) (Table 1).

Chylothorax was confirmed by a positive chylous test of the chest tube effusion.

Conservative treatments were initiated, including fasting, intravenous nutritional support, subcutaneous octreotide (0.1 mg tid), and chest perfusion with 50% hypertonic glucose to promote thoracic adhesion.

During conservative therapy, the drainage volume decreased and the fluid turned pale‐yellow. However, massive milky‐white effusion recurred after oral diet was resumed, indicating persistent chyle leakage.

Despite 1–2 weeks of conservative management, there was no significant reduction in chyle drainage, necessitating surgical intervention.

Olive oil (100 mL) was administered orally 6 h before reoperation to distend the thoracic duct. The milky‐white thoracic duct was identified in the supradiaphragmatic space between the anterior aspect of the azygos vein and posterior esophagus; ICG was not used for lymphatic visualization.

During surgery, fistula openings were identified at the intersection of the upper edge of the azygos arch and the anterolateral side of the trachea in the upper right mediastinum. Milky fluid continuously emerged from these fistulas, deviating from the normal anatomical pathway of the thoracic duct (Figure 1). The thoracic duct was dissected and ligated in the region of the costophrenic angle between the azygos vein and the aorta. Chyle leakage ceased immediately, and the fistulas were subsequently sutured. Postoperatively, patients resumed a normal diet, successfully had their chest tubes removed, and were discharged after uneventful recovery.

FIGURE 1.

Intra‐operative findings of chylous leakage in right upper mediastinum. The red arrow shows the region of right upper mediastinal lymph‐node dissection with visible chylous fluid. The blue arrow points to the chylothorax fistula. Representative images from Case 1 and Case 2 are presented.

Follow‐up data were collected. The two Stage‐IA patients have not developed tumor recurrence or metastasis. The Stage‐IIIA (N2) patient had negative genetic profiling and received adjuvant chemotherapy combined with immunotherapy. Brain metastasis occurred 18 months post‐operatively, treated with cranial radiotherapy. The patient is currently receiving chemotherapy and remains alive.

5. Discussion

In this study, three cases of significant postoperative chylothorax occurred on the right side, specifically in the lymph node dissection area of the right upper mediastinum. Related literature [4, 5] indicates a higher incidence of postoperative chylothorax following right lung cancer surgery compared with the left. This difference may be due to the broader mediastinal lymph node area on the right side, resulting in more branches of the right thoracic duct. The anatomical course of the thoracic duct itself is highly variable, and variations occur more frequently on the right side. The primary cause of postoperative chylothorax in lung cancer surgery is usually injury to thoracic duct branches [6]. Due to extensive communication between the thoracic duct, its branches, and mediastinal lymph nodes, these structures are easily damaged during mediastinal lymph node dissection. Akin et al. [7] suggest a close relationship between lymph node dissection and the development of postoperative chylothorax in lung cancer, particularly noting that group 4R lymph node dissection carries a higher risk of damaging thoracic duct branches. Liu et al. [5] performing prophylactic ligation of the thoracic duct branch during right pulmonary resection and mediastinal lymph‐node dissection is an effective and safe method of preventing postoperative chylothorax.

The fistulas observed in the three reported patients were located in the upper right mediastinal lymph node dissection region, consistent with previous studies. Additionally, during surgery in one patient, we identified a milky‐white tubular structure in the upper right mediastinum, presumed to be a variant lymphatic vessel (Figure 2). Therefore, surgeons should remain vigilant regarding potential thoracic duct variations when performing lymph node dissection in this region. Preventive ligation of suspicious thoracic duct branches, as illustrated in Figure 3, may be considered as a potential measure to avoid postoperative chylothorax and subsequent reoperation. Given the limited sample size of this case series without a control group, definite conclusions on its efficacy cannot be drawn.

FIGURE 2.

Aberrant lymphatic vessel identified in the right upper mediastinum. Labels indicate the trachea, abnormal lymphatic vessel, and arch of the azygos vein. This variant lymphatic structure was directly visualized intraoperatively in one patient.

FIGURE 3.

Preventive suturing at the intersection of the upper margin of the azygos arch and the anterolateral side of the trachea. Blue arrow marks the site for potential prophylactic suturing during extensive right upper mediastinal lymphadenectomy.

Currently, no unified consensus exists regarding the optimal management of postoperative chylothorax in lung cancer patients. Treatment options include conservative management and surgical intervention [8]. The primary goal of conservative management is to reduce chyle production and facilitate natural healing of the thoracic duct or its branches. Methods include a low‐fat diet or total parenteral nutrition, subcutaneous octreotide injections, and promoting thoracic adhesions. Although conservative management successfully resolves postoperative chylothorax in most lung cancer patients, a small subset does not respond adequately and requires surgery. At present, clear consensus on surgical indications and timing, particularly regarding drainage volume, is lacking. Drawing from experience in managing chylothorax following esophageal cancer surgery [9], some authors propose surgical intervention if daily chyle drainage remains > 10 mL/kg/day or 1000 mL/day after 48–72 h of conservative treatment. This approach prevents prolonged conservative management, reducing complications such as malnutrition and electrolyte imbalances.

The primary aim of surgery is to identify and seal the leakage site promptly. Thoracoscopic (VATS) thoracic duct ligation is currently preferred.

Therefore, based on our experience and relevant literature, we recommend heightened vigilance for variant lymphatic vessels when performing upper right mediastinal lymph node dissection. Preventive suturing may be considered at the intersection between the upper edge of the azygos arch and the anterolateral aspect of the trachea in extensive dissections (Figure 3). If substantial chylous drainage persists after 72 h of conservative treatment, intraoperative injury to variant lymphatic vessels should be suspected, and prompt surgical intervention should be performed. Early surgical intervention reduces hospital stay, treatment costs, and patient distress.

6. Conclusion

Postoperative chylothorax in lung cancer is associated with lymph node dissection. Injury to variant lymphatic vessels frequently results in significant chylothorax, necessitating further surgery. Three cases of chylothorax after lung cancer surgery may be attributable to lymphatic vessel variation in the upper right mediastinum.

These variant vessels are typically located in the upper right mediastinum, at the intersection of the upper edge of the azygos arch and the anterolateral side of the trachea. Therefore, during extensive lymph node dissection in the upper right mediastinum, preventive suturing may be considered at this intersection to minimize the risk of postoperative chylothorax.

Author Contributions

Xiaoyun Li: writing – original draft, writing – review and editing, formal analysis. Mei Xu: investigation, validation, visualization. Mingyu Fan: methodology, data curation, software, supervision. Xiaojun Tang: conceptualization, project administration, funding acquisition, resources.

Funding

The authors have nothing to report.

Ethics Statement

This study was approved by the Ethics Committee of West China Hospital, Sichuan University (20241016).

Consent

Written informed consent for publication of their clinical data was obtained from all individual patients included in this case series. All procedures performed in this work were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.