Robotic subxiphoid surgical approach for mediastinal lesions: One-year experience

Abstract

BACKGROUND

Median sternotomy has been considered the gold standard approach for anterior mediastinal tumor resection. However, recent advances in video-assisted thoracoscopic surgery and robotic-assisted thoracoscopic surgery with carbon dioxide insufflation have allowed minimally invasive approaches even for large and locally invasive tumors of the upper-anterior mediastinum. The subxiphoid robotic optical approach is a recently developed technique for accessing the mediastinum. The trans-subxiphoid technique offers excellent exposure of the surgical field, reduces postoperative pain, facilitates specimen retrieval even for large tumors, and potentially improves early surgical outcomes.

AIM

To evaluate the safety, feasibility, and outcomes of a robotic subxiphoid approach for the resecting of large/invasive mediastinal tumors.

METHODS

Between July 2024 and September 2025, 12 patients underwent subxiphoid robotic mediastinal resection. The diameter of the operated lesions ranged from 30 mm to 70 mm. A 3 cm subxiphoid incision was made at the subxiphoid level for GelPort placement, allowing for optical port access. Two operating ports were placed at the sixth intercostal space bilaterally. Carbon dioxide insufflations (8-10 mmHg) enlarged the surgical field, improving visualization of critical anatomical landmarks, such as the internal mammary arteries and phrenic nerves. This approach allowed complete resection of large or invasive tumors, preserving thoracic stability and reducing the risk of postoperative myasthenic crisis.

RESULTS

The mean operating time was 170.2 minutes, and the median hospital stay was 3.5 days. No major postoperative complications occurred. Two conversions were necessary: One with a lateral robotic approach due to previous abdominal surgery, and one with a sternotomy for tumor invasion of the aortic arch. Histopathological analysis identified nine thymomas and one solitary fibrous tumor.

CONCLUSION

Subxiphoid robotic approach is a safe, effective technique for extended thymectomy, fulfilling both oncological and myasthenia gravis surgical objectives.

Key Words: Robotic surgery; Thymectomy; Subxiphoid approach; Robotic thymectomy; Multiport robotic thymectomy; Optical subxiphoid thymectomy

Core Tip: The subxiphoid robotic-assisted thoracic approach is an excellent alternative to traditional unilateral robotic and video-assisted minimally invasive techniques for the treatment of anterior mediastinal tumors. This method provides an unobstructed view of the mediastinal structures, allowing for the safe removal of larger lesions while maintaining direct control over both phrenic nerves. Furthermore, it is associated with less postoperative pain and better cosmetic outcomes. Based on our initial experience with 10 patients, the subxiphoid approach is a feasible, safe, and oncologically sound option for mediastinal dissection, even in cases where lesions exceed 5 cm in diameter.

INTRODUCTION

Thymectomy is a well-known approach to the surgical management of anterior mediastinal masses, particularly thymomas and thymic hyperplasia, in patients with myasthenia gravis. Median sternotomy has always been considered the gold standard, providing the best window view for mediastinal structures; however, it is associated with significant surgical trauma, increased postoperative pain, prolonged hospital stays, and increased complications[1]. With the continuous evolution of minimally invasive thoracic surgery, it is changing the face of surgery and promoting approaches that reduce surgical risk while maintaining oncological efficacy. This shift enabled one of the hallmark methods, which allows for less blood loss during surgery, shorter hospitalization times, and better cosmetic results compared to open surgeries[2,3]. Unilateral intercostal video-assisted thoracoscopic surgery (VATS) is described as associated with postoperative neuralgia and a limited view of both phrenic nerves[4].

The subxiphoid VATS approach thus allowed direct access to the anterior mediastinum without requiring any intercostal cuts. Here, there is broad exposure to both pleural cavities, allowing easy en bloc resection of thymic tissue together with the surrounding adipose tissue, significantly reducing postoperative pain and discomfort[5,6]. The use of robotic-assisted thoracic surgery (RATS) has really taken the advantages of minimally invasive techniques to the next level. These robotic systems offer a three-dimensional view, help reduce tremor, and come with wristed instruments, which allow for precise dissection in those tricky, hard-to-reach areas of the chest. This is particularly useful in thymic surgery, where careful handling near the innominate vein, phrenic nerves, and pericardium is essential. Numerous studies and meta-analyses have demonstrated that robotic thymectomy is associated with reduced intraoperative blood loss, fewer complications, shorter hospital stays, and lower rates of incomplete resection compared to sternotomy, while maintaining operative times comparable to VATS[7-9]. The robotic subxiphoid approach represents a further evolution in minimally invasive access to the mediastinum. Carbon dioxide (CO₂) insufflation, while maintaining double-lung ventilation, expands the retrosternal space, creating a spacious operative field with excellent visualization of both the pleural cavities and the phrenic nerves. This configuration really helps to reduce postoperative pain[10,11]. The enhanced dexterity of robotic instruments, combined with their advanced optics, makes it much easier to carefully dissect the upper thymic poles. This means that we can perform a radical thymectomy without having to extend the cervical area[12]. Recent clinical experiences suggest that this technique has the potential to improve perioperative outcomes, increase patient satisfaction, and preserve oncologic effectiveness. This study shares insights from a single-center experience, assessing the safety, feasibility, and clinical outcomes of robotic subxiphoid thymectomy, thus providing additional evidence to support this emerging technique[13].

MATERIALS AND METHODS

A retrospective, single-center study began the initial experience with the robotic subxiphoid approach for anterior mediastinal lesions. Twelve patients who underwent surgery between July 2024 and September 2025 at the Division of Thoracic Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori (Milan, Italy), were selected. Standardized procedures are always preferable, and therefore, all surgeries were performed by a single surgical team using the da Vinci Xi robotic system. Inclusion criteria consist of patients aged 18 years or older with a solitary anterior mediastinal lesion deemed suitable for minimally invasive resection, having no history of sternotomy or thoracic surgery, and an American Society of Anesthesiologists score of III or less. Exclusion criteria include: Extensive mediastinal invasion requiring open access; severe cardiopulmonary comorbidities with general anesthesia; chest wall deformity; previous abdominal surgery. All patients underwent a standardized preoperative assessment, which included a chest computed tomography scan and a positron emission tomography-computed tomography scan. Magnetic resonance imaging was performed explicitly in cases where vascular invasion was suspected. Pulmonary and cardiac evaluations were performed to assess and confirm each patient’s suitability for surgery. The study was conducted in accordance with the principles outlined in the Declaration of Helsinki. The study was reviewed and approved by the Institutional Review Board of Fondazione IRCCS Istituto Nazionale dei Tumori. Written informed consent was obtained from all participants for the surgical procedures and for the use of their data for research purposes. Demographic, clinical, operative, and postoperative information was retrospectively collected from institutional medical records.

Surgical technique

Patient position: All patients were placed in the supine position, with a roll positioned beneath the back at the level of the lower third of the sternum to enhance exposure of the subxiphoid margin. The left arm was extended and rested on a padded L-shaped support, while the right arm was positioned on a padded bar adjacent to the patient’s right side (Figure 1A).

Figure 1 Stepwise illustration of the subxiphoid robotic-assisted thoracic surgery approach. A: Patient position for the subxiphoid robotic-assisted thoracic surgery (RATS) approach; B: The gel port is positioned through the subxiphoid incision, with the carbon dioxide tubing connected to maintain insufflation during the robotic-assisted procedure; C: Port configuration for the subxiphoid RATS approach. The gel port is positioned through the subxiphoid incision and connected to the carbon dioxide insufflation line to maintain the operative field. Two additional trocars are placed - one on the right and one on the left side - to allow optimal access for the robotic instruments; D: The robotic system operating during the subxiphoid RATS.

Anesthetic management: Anesthetic management for robotic thoracic surgery followed similar protocols to those employed in open and VATS procedures[14]. All patients underwent general anesthesia with a double-lumen endotracheal tube. During the procedures, we ventilated both lungs; however, we switched to one-lung ventilation (OLV) when performing wedge resections or when a closer examination of the pleural cavity was required. During CO₂ insufflation, we used a protective ventilation approach, utilizing low tidal volumes and allowing for mild hypercapnia to minimize the risk of barotrauma. We carefully monitored the EtCO₂ levels to prevent significant hypercapnia, adjusting the minute ventilation within safe pressure limits to effectively manage CO₂ retention[15,16]. Routine arterial blood gas analysis was conducted to inform our ventilatory management.

Port placement and docking: The procedure began with a 3 cm transverse incision, positioned 1 cm below the xiphoid process. The rectus abdominis fascia was cut vertically, and the muscle was gently detached from the xiphoid. Finger blunt dissection was performed to free the posterior surface of the sternum. A GelPort single-port device was introduced through the subxiphoid incision, allowing for CO₂ insufflation at 8-10 mmHg (Figure 1B). The mediastinal pleura was dissected to obtain bilateral entry into the thoracic cavity. Robotic ports were placed through two additional 1 cm skin incisions in the sixth intercostal space along the midclavicular line on each side (Figure 1C). The da Vinci Xi surgical system (Intuitive Surgical, Sunnyvale, CA, United States) was docked using three arms: Arm 1: An 8-mm port was positioned in the right sixth intercostal space along the midclavicular line. Arm 2: An 8-mm port was placed in the subxiphoid region and housed the camera with a 30° oblique view. Arm 3: An 8-mm port was positioned in the left sixth intercostal space along the midclavicular line. Docking time was under 5 minutes in all the procedures. A fenestrated bipolar forceps was introduced through the left port, while a bipolar Maryland dissector was inserted through the right port (Figure 1D).

Surgical steps: The procedure began with a careful blunt dissection of the tissues located beneath the sternum, starting at the lower end and proceeding upward toward the manubrium (Figure 2). This method, combined with CO₂ insufflation, created a large operative field in the anterior mediastinum, allowing clear visualization of important anatomical features, such as the internal mammary arteries and the phrenic nerves. Next, the inferior thymic horns were cut along the pericardial surface. To ensure safe and efficient hemostasis, we used Syncrosyl to divide the major arteries and veins supplying the mediastinal fat. Dissection was extended superiorly from the pericardium to expose the ascending aorta and the superior vena cava. Adhesions to the lung parenchyma were meticulously divided using either a bipolar Maryland instrument or Syncrosyl. After dissecting the mediastinal tissue away from the right phrenic nerve, the dissection proceeded in a cranial direction from the superior vena cava to identify and expose the innominate vein. With the innominate vein clearly visualized, the upper thymic horns were removed from the neck using blunt dissection directly above the vein. The thymic vein was divided using Syncrosyl, eliminating the need for additional hemostatic devices, such as clips or Hem-o-lok. Finally, the resected specimen was extracted from the chest cavity through the subxiphoid utility incision using an endoscopic retrieval bag.

Figure 2 The procedure began with a careful blunt dissection of the tissues located beneath the sternum, starting at the lower end and proceeding upward toward the manubrium.

Preference cards: (1) 30-degree 10 mm robotic camera; (2) CO₂ insufflation device (8-10 mmHg); (3) Tissue retractor: GelPort (Applied Medical, CA, United States), robotic trocars; (4) 8 mm robotic instruments: EndoWrist bipolar Maryl, Fenestrated bipolar forceps, and Synhroseal; and (5) Endoscopic retrieval bag.

Statistical analysis

The following parameters were analyzed: Patient age, sex, lesion size, histopathological diagnosis, Masaoka stage (for thymomas), operative time, postoperative complications, conversion to alternative approaches, and length of hospital stay. Continuous variables are presented as mean or median values, while categorical variables are reported as frequencies.

RESULTS

A total of 12 patients (9 females, 3 males; mean age 55.2 ± 15.6 years; range 29-77 years) underwent robotic subxiphoid resection of anterior mediastinal lesions during the study period. The mean maximal lesion diameter was 39.0 ± 22.0 mm (range 14-70 mm).

Operative outcomes

The mean operative time was 202.9 ± 44.6 minutes (range 99-290 minutes). The median length of the postoperative hospital stay was 3.58 ± 1.4 days (range 2-4 days). No major postoperative complications were observed. Two conversions occurred: One to a lateral robotic approach due to adhesions from prior abdominal surgery, and one to sternotomy because of tumor invasion of the aortic arch.

Histopathological findings

Histological examination revealed nine thymic lesions (including thymomas of different subtypes, thymic hyperplasia, and cysts) and one solitary fibrous tumor. Among the thymomas, Masaoka staging showed two cases at stage IIA and one case at stage IIB.

When stratified by diagnosis, operative and perioperative outcomes were consistent across subgroups (Table 1). Thymomas represented the majority of cases, with a mean lesion diameter ranging from 9 mm to 70 mm. Patients with thymic hyperplasia had the largest mean lesion size (69 mm), while those with micronodular thymoma and thymic cysts had the smallest.

Table 1 Patients’ outcomes, mean ± SD.

Number	Sex	Age (years)	Diameter lesion (mm)	Operation time (minutes)	Diagnosis	Masaoka stage	Hospital stays (days)
1	Female	77	60	290	Thymoma AB	IIA	6
2	Male	44	32	220	Thymoma AB	IIA	4
3	Female	53	53	185	Thymoma cyst	N/A	5
4	Female	62	9	180	Thymoma A	I	5
5	Female	29	68	210	Thymic hyperplasia	N/A	5
6	Male	66	18	230	Thymoma cyst	N/A	4
7	Female	74	14	180	Thymic cyst	N/A	3
8	Female	29	70	197	Thymic hyperplasia	N/A	3
9	Male	60	36	180	Micronodular thymoma	IIb	2
10	Female	61	30	252	Thymoma B1	IIa	3
11	Female	67	50	212	Thymoma B1-B2	IIb	2
12	Female	40	15	99	Thymoma B2	I	1
		55.2 ± 15.6	37.9 ± 20.9	202.9 ± 44.6			3.58 ± 1.4

N/A: Not applicable.

Correlation between lesion size and operative time

A scatterplot was created to examine the association between lesion size and surgical duration (Figure 3). Although no definitive linear correlation was observed, larger lesions generally demanded longer operative times, especially in the thymoma subgroup. This confirms that even relatively large anterior mediastinal masses can be safely resected through the subxiphoid robotic approach without significant prolongation of surgical duration.

Figure 3 Scatter plot of operative time vs lesion diameter.

DISCUSSION

Robotic subxiphoid thymectomy is a safe and effective method for removing lesions in the anterior mediastinum. Using a subxiphoid view along with two operative thoracic trocars, this technique achieves outstanding perioperative results, significantly reducing surgical trauma, postoperative pain, and the length of hospital stays compared to traditional sternotomy. Systematic reviews consistently show that robotic thymectomy reduces hospital stay by roughly three days and yields reduced intraoperative blood loss relative to transsternal surgery[17,18]. Our recorded median hospital stay of 3.58 ± 1.4 days aligns with these findings. Notably, no significant postoperative complications occurred within our group, highlighting the safety of this technique in appropriately selected patients.

A key advantage of the subxiphoid robotic approach is its capability to be performed without extensive OLV. Standard VATS and lateral robotic approaches usually require OLV to optimize the surgical field; however, OLV carries considerable risks, including hypoxemia, hypercapnia, barotrauma, and postoperative pulmonary complications, especially in elderly patients or those with pre-existing respiratory disease[19-22]. On the other hand, using CO₂ insufflation through the subxiphoid port creates a spacious area behind the sternum while still allowing ventilation in both lungs. This approach simplifies anesthesia management, reduces risks associated with ventilation, and opens up the option for minimally invasive thymectomy to patients who might not be suitable for traditional VATS or robotic thoracic surgeries.

Compared to VATS, robotic surgery offers superior visualization, enhanced instrument dexterity, and greater precision within the anterior mediastinum. These advantages facilitate the performance of dissections near important anatomical features, such as the phrenic nerves and the innominate vein. Although systematic reviews find similar complication rates and lengths of stay between VATS and RATS, robotic techniques have demonstrated lower conversion rates to open surgery and shorter chest drainage durations in select patient series[23-27].

This method provides a clear view of both pleural cavities, facilitating the removal of thymic tissue more completely and simplifying sample extraction without the need to spread the ribs. Comparative studies have also demonstrated that robotic techniques are associated with lower postoperative pain scores and greater cosmetic satisfaction, particularly when compared to traditional sternotomy[28,29].

In our study, stratification of outcomes by histological diagnosis (Table 1) confirmed the reproducibility of the results across various subgroups. Thymomas comprised the majority of cases; however, even larger lesions, such as thymic hyperplasia, averaging 69 mm in diameter, were successfully removed within reasonable operative times. The scatterplot (Figure 2) illustrates the relationship between lesion diameter and operative time (coefficient of determination (R² = 0.12). To assess this association quantitatively, a linear regression analysis was conducted. The resulting regression line displays a positive coefficient, indicating that operative time tends to increase as lesion size grows. This statistical finding is consistent with the visual trend observed in the graph and suggests that, although larger lesions may extend the duration of surgery, the increase remains moderate. The gentle slope of the regression line further highlights the technical feasibility of the surgical approach, even in cases involving substantial lesion dimensions. In our series, the mean operative time was 202.9 ± 44.6 minutes, consistent with previously published data on robotic thymectomy via subxiphoid access[23-25]. The mean lesion diameter measured 37.9 ± 20.9 mm, confirming that even relatively large anterior mediastinal masses can be safely and effectively resected using this approach.

In addition to its practical feasibility, the subxiphoid approach may offer financial benefits by reducing the need for postoperative pain. However, bringing robotic systems on board comes with a hefty upfront cost and demands specialized training programs, which can be difficult to manage in environments with limited resources. It is also important to consider the learning curve associated with this approach, as it could impact operational times and clinical results during the early stages of implementation.

While our findings are promising, the study’s constraints - including a small sample size, a brief follow-up period, and a single-institution design - limit the applicability of the results. To better define the role of subxiphoid RATS in clinical practice and evaluate its long-term oncologic efficacy, substantially larger, multicenter, prospective trials with prolonged follow-up are essential. Our data support the expanding body of evidence that robotic subxiphoid thymectomy is a safe and effective minimally invasive option for anterior mediastinal lesions, including sizable thymic tumors. The combination of reduced surgical trauma and favorable perioperative outcomes positions this technique as an encouraging advance in the field of minimally invasive mediastinal surgery.

CONCLUSION

Our initial experience demonstrates that robotic subxiphoid thymectomy is both technically feasible and oncologically effective for treating anterior mediastinal lesions. It provides superior intraoperative visualization, reduces postoperative pain, and results in shorter hospital stays. The ability to avoid intercostal incisions and prolonged OLV represents a significant advantage over lateral approaches. However, limitations persist, including the small cohort size, single-center scope, and lack of long-term follow-up. Moreover, the sharp learning curve and significant costs associated with robotic platforms may impede broad adoption. Future multicenter prospective studies with larger patient populations are needed to validate the oncologic outcomes and costeffectiveness of subxiphoid RATS in thymic surgery.