Laparoscopic resection of gastric schwannoma: a case description

Introduction

Gastric schwannoma (GS), a rare mesenchymal tumor arising from Schwann cells within the gastric plexuses, accounts for 0.2% of primary gastric cancers and 6.3% of all gastric mesenchymal tumors (1). GS predominantly affects women over the age of 40 years, and the majority of these tumors are benign. Characterized by slow progression, GSs are associated with a low risk of recurrence or metastasis. Typically, these tumors present with nonspecific symptoms and are frequently misdiagnosed as gastrointestinal stromal tumors (GISTs) prior to surgical intervention.

On April 23, 2024, a patient was admitted to Tongxiang First People’s Hospital with a gastric mass and underwent surgical resection. The postoperative diagnosis confirmed GS. Here, we summarize our diagnostic and treatment experience with this patient.

Case presentation

A 73-year-old male patient was admitted with a chief complaint of gastric mass discovered by B-ultrasonography 10 days prior. The patient had no fever, abdominal pain, hematemesis, or black stools.

The patient’s height was 168 cm, and his weight was 61 kg. He was conscious, his superficial lymph nodes were not enlarged, and no abnormalities were found in heart or lung examinations. His abdomen was soft, without any tenderness or rebound, and there was no palpable mass on digital rectal examination.

Laboratory examinations showed that white blood cells, red blood cells, hemoglobin, platelets, and concentrations of C-reactive protein concentration, carcinoembryonic antigen, cancer antigen 125, carbohydrate antigen 19-9, and alpha fetoprotein were all within normal range. The result of the fecal occult blood test was negative. Gastroscopy revealed a giant uplift with a central depression on the anterior wall of the gastric body (Figure 1). Computed tomography (CT) of the abdomen revealed a mass on the lateral aspect of the lesser curvature of the stomach with several dense, unevenly enhanced areas on contrast-enhanced CT, suggestive of a possible GIST or GS (Figure 2).

Figure 1 Gastroscopy. (A,B) Gastroscopy revealed a giant uplift with a central depression on the anterior wall of the gastric body.

Figure 2 Abdominal CT. (A,B) Abdominal CT revealed a mass on the lateral aspect of the lesser curvature of the stomach with several dense, unevenly enhanced areas on contrast-enhanced CT, suggestive of a possible GIST or GS. CT, computed tomography; GIST, gastrointestinal stromal tumor; GS, gastric schwannoma.

Laparoscopic surgery was performed on the third day of admission. During the procedure, a yellowish-white, solid mass was identified on the anterior wall of the gastric body adjacent to the lesser curvature. The tumor was exophytic, had a firm texture, and was clearly demarcated. The lesser curvature was isolated and skeletonized, and the tumor was excised with a 2-cm margin of healthy gastric tissue using high-intensity focused ultrasound (HIFU). The resected tumor was then placed in a laparoscopic protective sleeve. The incision at the umbilicus was extended to facilitate en bloc removal of the tumor, measuring approximately 8 cm × 5.5 cm × 4 cm in size (Figure 3). The wound was closed using 3-0 knotless sutures. Microscopically, the tumor cells were densely packed and arranged in a fusiform pattern with minimal nuclear atypia. Histopathological examination confirmed a diagnosis of GS and the resection margins were negative. Immunohistochemical staining was negative for CD117, CD34, DOG-1, smooth muscle actin (SMA), desmin, and positive for S-100 (Figure 4). The Ki-67 index was 5%. The patient was discharged from our hospital on postoperative day 7 without experiencing any complications such as postoperative gastric bleeding, delayed gastric emptying, intestinal obstruction, or incision infection.

Figure 3 Intraoperative view. (A) A yellowish-white solid mass was identified on the anterior wall of the gastric body adjacent to the lesser curvature. (B,C) The tumor was exophytic, had a firm texture, and was clearly demarcated. The tumor measured approximately 8 cm × 5.5 cm × 4 cm in size.

Figure 4 Postoperative pathology and immunohistochemical results. (A) Histopathological examination confirmed a diagnosis of GS (hematoxylin-eosin, ×200). (B) Immunohistochemical staining was positive for S-100 (×100). GS, gastric schwannoma.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

First described by Daimaru et al. in 1988, GS is a rare neoplasm (2). Patients with GS often lack specific clinical manifestations and may present with epigastric fullness and vague pain. As the tumor enlarges, it may compress surrounding structures or induce avascular necrosis, leading to symptoms such as an abdominal mass, obstruction, and hemorrhage. Some tumors remain asymptomatic and are incidentally discovered as gastric masses during routine health examinations. GS predominantly affects women between the ages of 40 and 60 years and typically presents as a solitary mass located primarily in the stomach body, with fewer occurrences in the antrum and pylorus (3,4). According to the growth pattern, GSs can be categorized into intraluminal, extraluminal, and mixed types, with the extraluminal and mixed types being more common (5). On CT, GSs appear as round, oval, or lobulated soft tissue masses that protrude from the stomach wall. These masses typically have smooth contours and well-defined margins, displaying either exophytic or mixed growth patterns. CT scans may show slightly hypodense shadows on noncontrast images, while postcontrast images often reveal slow, mild enhancements. Generally, GSs do not exhibit hemorrhage, necrosis, cystic changes, or calcifications, and they do not invade or metastasize to adjacent tissues. Gastroscopy often reveals a submucosal bulge with an intact superficial mucosa. If the tumor grows sufficiently large enough to compress the gastric mucosa, it may induce ischemia on the mucosal surface, reducing its resistance to gastric acid and potentially leading to ulcer formation (6). GSs are typically found in the submucosal layer, which can pose challenges for biopsy procedures (7). Endoscopic ultrasound (EUS) typically shows these tumors as being round or oval hypoechoic, homogeneous masses originating from the muscularis propria. Variability in echogenicity may occur due to intracapsular hemorrhage or necrosis in rare cases. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy has been deemed to be a reliable and effective means to histologically evaluating these gastric submucosal tumors. However, for malignant variants, needle biopsy poses a risk of tumor rupture and potential dissemination of cancer cells (8). Macroscopically, GSs usually present as solitary, round, or oval masses with well-defined borders but lacking a prominent capsule. They have a firm or hard texture and exhibit a grayish-white or grayish-yellow color. Microscopically, the tumor cells are densely packed and arranged in a fusiform pattern with lightly stained cytoplasm and minimal nuclear atypia. A notable histological feature is the presence of lymphocyte infiltration and the formation of a peripheral lymphocyte sleeve (9). Immunohistochemically, GSs demonstrate a strong positive expression of S-100 protein but a negative expression of CD117, DOG-1, CD34, platelet-derived growth factor A (PDGF-α), and myogenic markers; these constitute key diagnostic criteria and can aid in the differentiation of GSs from other mesenchymal tumors.

GSs should be differentiated from GISTs, gastric leiomyoma (GL), gastric ectopic pancreas (GEP), and other related diseases. GISTs, the most prevalent mesenchymal tumors of the digestive tract, account for 60% to 70% of such cases in the stomach, primarily in the submucosa. Although GSs are frequently misdiagnosed as GISTs, the latter are typically solitary and exhibit heterogeneous density. Hemorrhage, necrosis, and cystic changes can lead to uneven enhancement of GISTs. Both GISTs and GSs share overlapping clinical, radiological, and endoscopic or EUS characteristics, necessitating pathological evaluation for accurate differentiation. GISTs are generally dark red or hemorrhagic, lack a palisade structure, seldom exhibit lymphoid tissue at the margins, consistently express strong CD117 and DOG-1 positivity, show variable CD34 expression, and lack S-100 staining. Most GISTs harbor activating mutations in KIT and PDGFRA (10). GL is a benign mesodermal tumor usually solitary, typically occurs in the cardia and gastric fundus, and frequently presents without distinct clinical symptoms. It tests positive for desmin and SMA. GEP predominately develops in the stomach, duodenum, and proximal jejunum, manifesting as an oblate or hemispherical submucosal bulge on endoscopy, often with a central ductal opening and a characteristic umbilical depression.

GS is generally benign, with a favorable prognosis and low recurrence rate. Surgical approaches can be tailored according to the tumor’s location, size, and texture. With advancements in endoscopic technology, procedures such as endoscopic submucosal dissection (ESD) and endoscopic full-thickness resection (EFR) have become standard treatments for GS. These methods are characterized by minimal trauma, an expedited recovery, fewer complications, and reduced costs. Endoscopic resection is preferred when the lesion is small, arises from the submucosa or muscularis propria, and is located on the greater curvature or anterior wall of the stomach (11). However, surgical intervention is preferred if endoscopic resection is impractical or if preoperative assessments suggest incomplete resectability, particularly when the tumor is situated within the muscularis propria and exceeds 3 cm in diameter (8). For large GSs with an extraluminal growth pattern, endoscopic resection is challenging and associated with a higher complication rate. En bloc resection of the tumor, excluding lymph node dissection, can be performed based on the tumor’s size, location, growth pattern, and involvement of adjacent structures. Surgical alternatives include laparoscopic or open gastric wedge resection, partial gastrectomy, proximal or distal gastrectomy, and total gastrectomy. Laparoscopic resection of GS offers benefits over open surgery, such as reduced bleeding, less postoperative pain, faster recovery, and shorter hospital stays.

Acknowledgments

None.

Footnote

Funding: This study was supported by the Clinical Research Fund Project of Zhejiang Medical Association (No. 2021ZYC-A173).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-1217/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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