Submucosal Tunnel Endoscopic Resection of Giant Leiomyoma of the Esophagus Combined with Circular Arc Incision and 3D Volume Rendering

Summary

The protocol describes the detailed steps for treating patients with giant esophageal leiomyoma (GEL, > 10 cm) and achieving complete resection safely and effectively using endoscopic submucosal tunneling and resection.

Abstract

Esophageal leiomyoma is a common benign tumor of the esophagus. Traditionally, surgical resection is performed for large lesions. In this case, a 19-year-old male patient with a GEL underwent three-dimensional volume rendering to assess the surrounding structures, followed by submucosal tunneling and resection (STER). A modified arc-shaped mucosal incision was designed to provide sufficient exposure for dissection and complete removal of the lesion. Postoperative pathology confirmed leiomyoma. The patient resumed oral intake on postoperative day 2 and was discharged on day 5. STER creates a submucosal tunnel between the mucosal and muscular layers of the digestive tract and is mainly used for removing small esophageal and cardia submucosal tumors originating from the muscularis propria. It offers several advantages, including a short operation time, minimal trauma, rapid recovery, and no visible scars. In this case, STER was successfully applied to remove a large lesion, indicating that endoscopic treatment of GEL is both safe and feasible. However, further experience is required to evaluate its long-term efficacy.

Introduction

Giant esophageal leiomyoma is generally defined as a tumor measuring ≥10 cm in diameter and represents a rare benign neoplasm arising from the muscularis propria of the esophagus^1,2. Although most esophageal leiomyomas exhibit indolent growth and minimal malignant potential, large tumors may cause progressive dysphagia, retrosternal discomfort, and even compression of adjacent mediastinal structures, rendering management technically demanding. Conventional treatment consists of open thoracotomy or thoracoscopic enucleation, and in selected cases partial esophagectomy. While these approaches provide reliable oncologic clearance, they are associated with substantial surgical trauma, prolonged recovery, pulmonary complications, anastomotic morbidity, and potential impairment of postoperative quality of life. Accordingly, there has been increasing interest in developing less invasive yet effective alternatives that allow complete resection with adequate pathological evaluation.

With the evolution of peroral endoscopic tunneling techniques, Submucosal Tunneling Endoscopic Resection (STER) has emerged as a minimally invasive option for subepithelial lesions (SELs) originating from the muscularis propria. The fundamental principle of STER is mucosal preservation: a mucosal entry is created proximal to the lesion, a submucosal tunnel is established, and the tumor is resected en bloc within the tunnel while maintaining mucosal integrity. The mucosal entry is subsequently closed with endoscopic clips, thereby reducing the risk of mediastinal contamination and perforation³. Previous studies have demonstrated that STER achieves high en bloc resection rates with low complication rates in esophageal and cardiac muscularis propria tumors measuring ≤3–5 cm. Compared with conventional thoracic surgery, STER offers the advantages of minimal invasiveness, absence of external incisions, shorter hospital stay, faster recovery, and superior functional preservation⁴ .

However, as tumor size increases, the limitations of the standard longitudinal or inverted T-shaped mucosal incision become more apparent. The confined tunnel space may restrict maneuverability, complicate specimen retrieval, and increase the risk of mucosal injury or incomplete resection. Consequently, for giant esophageal leiomyomas, thoracoscopic or open surgical resection is still considered by many to be a more secure option⁵. Expanding the applicability of STER to larger lesions while maintaining its minimally invasive benefits remains a critical technical challenge.

Against this background, the present study aims to evaluate the feasibility and safety of a modified arc-shaped mucosal entry in STER for giant esophageal leiomyomas, and to analyze its technical advantages in terms of improved exposure, facilitated specimen extraction, and more efficient closure. By increasing the effective opening area, the arc-shaped incision creates a broader operative field and better alignment between the tunnel entrance and the esophageal lumen, thereby enhancing dissection and traction of large tumors. In addition, the curved margins allow stepwise clip approximation with reduced tension, potentially improving closure security.

In terms of indications, STER is primarily suitable for SELs arising from the muscularis propria without evidence of mucosal invasion, particularly in anatomical locations amenable to stable tunnel creation, such as the esophagus, cardia, lesser curvature of the gastric body, gastric antrum, and rectum. Conversely, when preoperative imaging suggests unclear boundaries with major vessels, extraluminal extension, or severe submucosal fibrosis that precludes safe tunnel formation, alternative surgical approaches should be considered.

By reporting the procedural details and short-term outcomes of this modified arc-incision STER technique in a case of giant esophageal leiomyoma, we aim to provide technical insight and assist clinicians in determining the appropriateness and potential generalizability of this approach in similar clinical settings.

Case presentation:
A 19-year-old male was admitted for dysphagia and 10 kg weight loss over 1 year. Esophagogastroscopy revealed a giant GEL in the mid-esophagus (25 cm-34 cm from the incisors) with esophageal stenosis (Figure 1). Endoscopic ultrasound and contrast-enhanced computed tomography features suggested a possible leiomyoma (Figure 2). 3D Volume Rendering technology was used to reconstruct a stereoscopic image of the lesion and surrounding tissues and important blood vessels (Figure 3) to achieve a more accurate preoperative evaluation. After thorough discussion by a multidisciplinary team and communication with the patient, it was decided to perform resection by STER.

Diagnosis, Assessment, and Plan:
The patient was a 19-year-old male who presented with progressive dysphagia and intermittent retrosternal discomfort over several months, without weight loss, hematemesis, or constitutional symptoms. Physical examination was unremarkable. Given the obstructive esophageal symptoms in a young patient, upper gastrointestinal endoscopy was performed as the initial diagnostic test to directly visualize the lesion and assess mucosal integrity. Endoscopy revealed a large subepithelial protrusion in the middle-to-lower esophagus with intact overlying mucosa, suggesting a lesion originating from the deeper layers rather than a primary mucosal neoplasm. To further characterize the layer of origin, internal echogenicity, and relationship to adjacent structures, endoscopic ultrasonography (EUS) was conducted. EUS demonstrated a well-demarcated, hypoechoic mass arising from the muscularis propria, without evidence of mucosal invasion or enlarged regional lymph nodes. Contrast-enhanced chest computed tomography (CT) was subsequently performed to evaluate tumor size, mediastinal involvement, and possible compression of adjacent organs. CT confirmed a large intramural esophageal mass with clear boundaries and no signs of extraluminal invasion or distant metastasis. Three-dimensional volume rendering reconstruction was additionally applied to better delineate spatial relationships with the aorta, trachea, and other mediastinal structures, thereby facilitating preoperative planning and risk assessment.

Based on clinical presentation, endoscopic findings, and imaging characteristics, a presumptive diagnosis of giant esophageal leiomyoma was established. The differential diagnosis included gastrointestinal stromal tumor (GIST), schwannoma, granular cell tumor, and less likely, esophageal duplication cyst or leiomyosarcoma. The absence of irregular margins, cystic degeneration, necrosis, lymphadenopathy, or invasive features on imaging favored a benign smooth muscle tumor. Given the tumor’s large size and the patient’s symptomatic status, resection was indicated to relieve obstruction, obtain definitive histopathological diagnosis, and prevent further progression or potential complications such as bleeding or luminal obstruction.

Regarding the treatment strategy, conventional thoracoscopic or open surgical enucleation was considered; however, in view of the patient’s young age, absence of invasive features, and strong preference for a minimally invasive approach, Submucosal Tunneling Endoscopic Resection (STER) was selected. The rationale for Considering the lesion’s large size, a modified arc-shaped mucosal incision was designed to expand the effective entry area, improve instrument maneuverability, and facilitate en bloc resection and specimen retrieval. The mucosal entry was subsequently closed with endoscopic clips to minimize the risk of leakage and mediastinal contamination.

Potential intraoperative and postoperative complications were carefully evaluated, including bleeding, perforation, pneumomediastinum, subcutaneous emphysema, infection, mediastinitis, esophageal stricture, and incomplete resection. The patient was closely monitored postoperatively, with fasting, intravenous proton pump inhibitor therapy, and prophylactic antibiotics administered. Oral intake was gradually resumed after confirmation of clinical stability and absence of leakage.

Protocol

The patient provided written informed consent for the use of medical data. This manuscript reports a single clinical case and does not involve prospective clinical study, retrospective cohort analysis, or any experimental intervention beyond routine clinical management. Written informed consent for publication was obtained from the patient prior to manuscript submission. Therefore, there is no specific IRB approval number applicable to this report

1. Preoperative examination and resectability assessment

1. The patient completed routine blood tests, blood coagulation tests, an electrocardiogram, and pulmonary function tests before the operation. The patient was prohibited from eating for 8 h before the operation.
2. 3D Volume Rendering technology was used to reconstruct the three-dimensional images of the lesion and surrounding tissues and important blood vessels (Figure 3) to fully evaluate the adjacent relationship between the lesion and important blood vessels and tissues. It can be seen that the lesion is located between the aortic arch, pulmonary artery, and trachea, and the space at this location is narrow, so the lesion presents an endophytic growth pattern.
3. A sector scanning ultrasound endoscope was used to evaluate the layered structure of the lesion. Because the lesion was large, a sector scanning ultrasound endoscope was selected for further evaluation to ensure a clear far-field display. The main body of the lesion was seen to be located in the submucosa, and the boundary between the lesion and the muscularis propria was unclear in some areas. There was a distance between the lesion and the surrounding important blood vessels, which provides a basis for endoscopic submucosal dissection using the tunnel technique.

2. Surgical materials and patient preparation

1. Endoscopic image processing devices, injection needle, snare, incision knife, physiological saline for injection, methylene blue, epinephrine hydrochloride, metal clip, carbon dioxide insufflator, and accompanying water supply device were prepared.
2. Endotracheal intubation was performed under general anesthesia, and the patient was placed in the left lateral decubitus position.
3. The water and air supply functions of the gastroscope were checked.
4. The electrosurgical unit was set to Endocut (for cutting), 40 W, effect 3, cutting width 2, and cutting interval time 3.
5. Submucosal injection solution preparation: A mixed solution of 100 mL of normal saline, 0.1 mL of methylthioninium chloride, and 1 mg epinephrine hydrochloride was prepared.

3. Incision design and creation (Figure 3)

1. A comprehensive examination of the esophagus, stomach, and duodenum was performed to rule out multiple lesions or other diseases.
2. Suction was used to clear fluids and mucus from the pharynx and esophagus.
3. The location of the lesion was confirmed under white light endoscopy, and the endoscope's scale was recorded.
4. A mark was made with an electrotome 5 cm orally to the lesion to confirm the location of the incision in the esophageal lumen and plan the range and angle of the arcuate incision.
5. A prepared submucosal injection solution was administered using an injection needle along the margins of the marked area into the submucosal layer, thereby creating separation between the mucosal layer and the muscularis propria.
6. An electrotome was used to cut the mucosa at the marking points, incise into the submucosal layer, and create a smooth arcuate incision to form a semicircular mucosal flap at the incision site. The incision length was 2 cm (Figure 3),

4. Dissection of lesion

1. The gastroscope with a transparent hood attached was inserted into the submucosal layer along the incision, and a tunnel was gradually created, advancing towards the anal side within the tunnel.
2. Gradual dissection was done, and the lesion can be seen exposed.
3. The injection needle was inserted obliquely at an angle of approximately 30° into the tissue surrounding the lesion. The mixed solution was slowly injected until a bluish elevation appeared in the submucosal layer, indicating adequate lifting.
4. Injection was stopped once a sufficient cushion was formed between the lesion and the surrounding tissue; this distance did not exceed the diameter of the incision knife tip. The needle was reinserted about 0.5 cm adjacent to the previous injection site, and the process was repeated.
5. Dissection was started on the side of the lesion adjacent to the esophageal wall, followed by dissection along the side close to the muscularis propria.
6. During the dissection process, the pulsation of the abdominal aorta can be seen. The handling at this location should be very cautious, and a sufficient liquid cushion is needed to ensure a certain distance between the lesion and the serosal layer and blood vessels, reducing perforation and thermal injury.

5. Removal of lesion and closure of incision (Figure 4)

1. A large-caliber snare was selected and positioned around the midpoint of the lesion. Gently the snare was tightened to capture the main body of the tumor. Because the surface of the lesion is smooth, the snare may slip off easily. If repeated attempts fail to secure the lesion, brief electrocoagulation was applied for 1–2 s to allow the snare to adhere to the surface, thereby increasing friction and facilitating safe and effective removal.
2. Care should be taken with the force when dragging through the narrow part of the esophagus to avoid the snare damaging the specimen. Because there is tracheal intubation, there is no need to worry about the specimen falling into the airway.
3. High-frequency hemostatic forceps were used to electrocoagulate and stop bleeding of residual blood vessels in the tunnel.
4. Metal clips were used to gradually close the wound from the anal side to the oral side to ensure complete closure.
5. The wound surface was checked, and the gastric tube was placed into the gastric cavity.

6. Sample management

1. Photograph the specimen and record the dimensions.
2. Completely immerse the specimen in 4% neutral buffered formalin solution for fixation.

7. Intraoperative troubleshooting and operation

1. During the creation of the arched mucosal incision, inaccurate judgment of the incision direction or curvature may result in tunnel deviation or misalignment with the neoplasm.
   1. To prevent this, measure and mark both ends of the intended incision under endoscopic visualization before initiating the cut. Ensure that the entry direction is parallel to the long axis of the lesion and slightly deviated distally to facilitate tunnel establishment along the tumor. The curvature of the incision should remain moderate, maintaining a length that can be securely closed. It is advisable to begin with a small incision and extend it gradually if necessary.
2. When the lesion is large, tunnel narrowing may occur, leading to limited maneuverability and difficulty in traction.
   1. Maintain low-pressure CO₂ insufflation and adequate suction throughout the procedure to minimize mediastinal distention and visual interference from gas. Employ progressive dissection, beginning with complete mobilization of the oral side of the lesion to create sufficient operating space before proceeding distally.
   2. For areas where the membrane is thin and close to major vessels, prioritize mechanical separation. Use the dissection knife for blunt dissection and apply strong electrocoagulation cautiously. If prominent arterial pulsation or abnormal vessel wall texture is detected, stop deep dissection immediately and consult a vascular surgeon. Avoid blind cutting or coagulation of unidentified vessels.
3. For neoplasms that are large in volume or have a smooth surface and are not easy to grasp, the two ends of the arcing incision can be extended by about 0.5–1 cm to form a wider exit. Use a snare to encircle the irregular depressions on the surface of the lesion. Sometimes, even with this, the snare still cannot firmly fix the lesion. Power can be applied to the snare for brief electrocoagulation for 1–2 s to cause adhesion between the snare and the lesion, thereby facilitating removal.
4. If the above methods still fail to pass through stenosis, such as the pharynx and larynx, the lesion can be removed from the tunnel and placed into the stomach. The lesion is then placed in an endoscopic retrieval bag for smooth and complete removal.

8. Postoperative care

1. Intravenous antibiotics were administered to prevent infection. Vital signs and the color of gastric tube drainage fluid should be closely monitored.
2. The nasogastric tube was removed 24 h postoperatively, and a complete blood count test were performed to rule out bleeding or mediastinal infection. A chest CT scan was performed 1 week postoperatively.

Results

The surgery was successfully completed, and the specimen was completely removed. The total operation time was 150 min. The nasogastric tube was removed 24 h postoperatively, and a liquid diet gradually started. The patient was discharged smoothly on POD5. Postoperative chest CT suggested complete resection of the esophageal lesion. Pathology revealed leiomyoma, and immunohistochemical staining showed H-cald and α-SMA (diffuse+), CD117, Dog1, and CD34(-), Ki-67 (<1%+), SDH-B(-), PHH3 (mitotic figures <2/50HPF), and ...

Discussion

Esophageal leiomyoma is a common benign esophageal tumor, usually solitary, and mostly occurs in the middle and lower esophagus. Dysphagia, pain, and weight loss are the most common clinical manifestations⁶. Extremely rare esophageal leiomyomas grow to >10 cm and are called giant esophageal leiomyomas (GELs)^2,7. Most GEL patients experience symptoms such as dysphagia and chest tightness. In this case, the patient presented with dysphag...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1.5-mm Disposable mucosal incision knife	Anrei, HangZhou, China	EK-410D
A transparent cap	Top Corporation, Tokyo, Japan	Elastic Touch F-030
Endoscopic image processing device	Olympus (Japan)	CV-290
High Frequency Electrotome	Erbe, Tübingen, Germany	VIO 200 D
High-frequency hemostatic forceps	Olympus (Japan)	FD-410LR
metal clips	AGS, HangZhou, China	16mm,AG-51044-1950-135-16
Single Use Injector	MICRO-TECH(Nanjing)	IN02-25423230
Snare Master	MT, NanJing, China	MTN-PFS-A-28/23
standard gastroscope	Olympus	GIF-260J