Gastric diverticulum misdiagnosed as gastrointestinal stromal tumor: a case description

Introduction

A gastric diverticulum (GD) is a localized pouch-like dilatation or sac-like protrusion of the gastric wall, most commonly occurring in the cardia or fundus of the stomach; most GDs present as solitary, and represent a rare anatomical anomaly; the estimated prevalence of GD ranges from 0.013–2.6% (1). GDs are classified as acquired or congenital, as well as true or false (2). In the absence of infection, GDs are usually asymptomatic, and some studies have reported that the most common symptom of GDs is epigastric pain (3,4). In a few cases, patients develop complications such as ulceration, upper gastrointestinal bleeding, hemorrhage, perforation, and malignant transformation, which can be life threatening and require surgical intervention (5,6). Overall, the symptoms of GDs are diverse and non-specific. Endoscopy is the primary diagnostic method for GDs; the diverticulum can be visualized during gastroscopy, and its size and neck width, and the presence of other lesions can be evaluated. Computed tomography (CT) is not widely used in the diagnosis of GDs due to potential misdiagnosis. Indeed, there are multiple reports of GDs being misdiagnosed as left adrenal masses by abdominal enhanced CT (7-9).

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract (10), and account for approximately 1–3% of all gastrointestinal tract tumors (11). GISTs originate from Cajal mesenchymal stromal cells, and while GISTs can occur anywhere in the digestive tract (10), they occur most commonly in the stomach (accounting for approximately 60% of cases), followed by the small intestine (20–30% of cases), and occasionally the omentum, mesentery, and peritoneum (12,13). The global incidence of GISTs is estimated to be 7–15 cases per 1 million people per year (14,15). The clinical manifestations of GISTs vary depending on the location and size of the tumor. The most common clinical symptoms include gastrointestinal hemorrhage and subsequent anemia, followed by abdominal pain, palpable mass, weight loss, and obstruction (16). The clinical symptoms of GISTs also lack specificity, making differential diagnosis difficult in the early stages. Endoscopy plays a crucial role in making a definitive diagnosis, and biopsy can be performed for pathological examination if necessary. CT can identify metastatic foci, and thus plays an important role in differential diagnosis, treatment response assessment, and tumor recurrence identification (17).

In this article, we report and summarize the diagnosis and treatment of a patient with a GD, initially misdiagnosed as a GIST, to improve the differential diagnosis ability of clinicians in the diagnosis and treatment of patients. The effective combination of endoscopy and imaging can aid in early diagnosis and early treatment, and prevent unnecessary treatments.

Case presentation

The patient was a 38-year-old female. On July 17, 2023, a physical examination revealed a lump in the right breast. Two days later, the patient was admitted to The First Affiliated Hospital of Zhejiang Chinese Medical University. No other signs or symptoms of discomfort were observed. The patient underwent routine examinations, including mammography, ultrasound, and enhanced magnetic resonance imaging (MRI). The patient did not experience any epigastric discomfort, and no epigastric masses were found. The imaging revealed no relevant findings. A comprehensive diagnosis and contraindication evaluation were carried out at our hospital on July 20, 2023 under general anesthesia. The patient underwent right breast breast-conserving radical mastectomy, right axillary anterior sentinel lymph node biopsy, and fascial histoplasty. During postoperative follow-up on December 17, 2024, the patient complained of recurrent epigastric discomfort. The patient’s CA199 and carcinoembryonic antigen (CEA) tumor markers were elevated.

MRI of the epigastric abdomen on December 20, 2024 revealed a rounded abnormal signal shadow in the splenic and gastric hiatus. The diameter was about 13 mm on T2-weighted imaging. Ring enhancement was observed after contrast administration. The bottom of the stomach and gastric wall were not clearly demarcated (Figure 1). To determine the nature of the round-like signal shadow in the splenogastric hiatus and the presence of lymph node metastasis of breast cancer, the patient underwent a plain CT scan, as well as an enhanced scan of the whole abdomen, and positron emission tomography computed tomography (PET-CT). The whole abdominal CT scan did not reveal a round-like signal shadow in the splenogastric hiatus as suggested by the previous MRI examination (Figure 2). PET-CT revealed soft-tissue nodules in the splenogastric fundus hiatus, but the patient’s fluorodeoxyglucose F18 metabolism was not increased; thus, the possibility of a GIST was considered (Figure 3).

Figure 1 Abdominal MRI showing an abnormal rounded signal shadow in the splenogastric hiatus, and T2-weighted imaging showing a high signal, about 13 mm in diameter, ring-shaped enhancement after contrast administration. The abnormal rounded signal shadow in the splenogastric hiatus is poorly demarcated from the gastric wall at the base of the stomach. The arrow indicates the rounded signal shadow in the splenogastric hiatus. MRI, magnetic resonance imaging.

Figure 2 Abdominal CT findings. No abnormal signal shadow was observed in the splenogastric hiatus. CT, computed tomography.

Figure 3 Abdominal PET-CT findings. (A-C,G-I) Transverse, coronal, and sagittal planes showing no significant increase in fluorodeoxyglucose F18 uptake. (D-F) Transverse, coronal, and sagittal planes showing a soft-tissue density nodular shadow in the splenogastric hiatus, approximately 6 mm × 10 mm in size, with poor demarcation from the gastric wall. PET-CT, positron emission tomography computed tomography.

As the MRI, CT and PET-CT results were inconsistent, and the patient had a history of breast cancer, the possibility of lymph node metastasis of breast cancer could not be ruled out. To determine the nature of the disease, a multidisciplinary discussion was held between the Breast Surgery Department, the General Surgery Department, the Imaging Department, and the Gastroenterology Department. As a result, endoscopic ultrasound (EUS) was recommended for further diagnosis. The patient was examined by gastroscopy, which revealed a mucosal depression in the fundus of the stomach with a smooth surface and a diameter of about 1 cm (Figure 4A,4B). Longitudinal axis endoscopic ultrasonography (LAEUS) revealed no obvious space-occupying lesions outside the fundus of the stomach (Figure 4C,4D). Moreover, mini-probe EUS showed the localized thinning and loss of the intrinsic muscular layer, with a cross-sectional size of 0.6 cm × 0.5 cm, which was considered a GD (Figure 4E,4F).

Figure 4 Endoscopic and ultrasonographic findings. (A,B) Plain endoscopy showing a mucosal depression in the gastric fundus with a smooth surface, approximately 1 cm in diameter. (C,D) LAEUS showing no obvious occupying space-lesion outside the gastric fundus, only diverticulum was observed. (E,F) Mini-probe EUS showing a lesion with localized thinning and loss of the intrinsic muscular layer, with a cross-sectional size of 0.6 cm × 0.5 cm, protruding outward, a diagnosis of GD was considered. EUS, endoscopic ultrasound; GD, gastric diverticulum; LAEUS, longitudinal axis endoscopic ultrasonography.

All the procedures in this study were performed in accordance with the ethical standards of the Medical Ethics Review Committee of The First Affiliated Hospital of Zhejiang Chinese Medical University (No. 2025-KL-411-01), and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and any accompanying images. A copy of the written consent form is available for review by the editorial office of this journal.

Discussion

Various diagnostic tests, including imaging procedures, endoscopic evaluations, and tissue analyses, can be used to distinguish between GDs and GISTs. This approach is necessary due to the non-specific nature of the presenting symptoms. GISTs are typically diagnosed by upper gastrointestinal endoscopy, revealing submucosal masses. These masses are then localized by EUS, which can be used to identify solid hypoechoic masses of muscular origin. The diagnosis is subsequently confirmed by immunohistochemistry (CD117/DOG1 positivity), and genetic testing following a biopsy. GDs are typically diagnosed by barium meal imaging or endoscopy, both of which can reveal cystic projections on the posterior wall of the gastric fundus. EUS provides a comprehensive view of normal mucosa and full-layer structure, while CT and MRI can assist in lesion differentiation. GISTs typically manifest as solid masses with enhancement on imaging, while GDs are characterized by cystic cavities containing gas or fluid. Thus, a histopathological examination is paramount in confirming the diagnosis. GISTs shows spindle cells and gene mutations, while GDs typically show normal mucosa (18,19). It is generally easy to differentiate between GISTs and GDs, but difficulties can arise on imaging (e.g., if the gastric wall is contracted and the GD bulges out), in which case abdominal CT may misdiagnose the bulging GD as gastric mesenchymal tumors or enlarged lymph nodes outside the gastric wall. Such misdiagnoses can lead to unnecessary surgery, such as the resection of an asymptomatic GD. In this case, while gastroscopy is helpful for diagnosis, EUS was needed to rule out other lesions outside the gastric wall. EUS can be used to assess invasion within the wall of the gastrointestinal tract and determine whether the digestive tract layer is the origin of the mesenchymal tumors. EUS can also be used to guide biopsy and identify other submucosal tumors (9).

CT and LAEUS are valuable in the diagnosis of abdominal or extra-gastric wall lesions. Exogenous GISTs (i.e., GISTs in the omentum, mesentery, and peritoneum) have no specific clinical manifestations. CT can clearly show the lesion site, size, morphology, and anatomical hierarchical relationship with the surrounding organs, and thus is an important tool in the diagnosis, staging, and identification of exogenous GISTs. LAEUS is mainly used in the diagnosis of large deep lesions of the digestive tube wall (via scanning and puncturing), as well as extra-tubular lesions, and plays an important role in the diagnosis of diseases of the pancreatic and biliary system such as pancreatic and biliary tumors or pancreatitis (20,21).

Given the patient’s medical history, the presence of a rounded abnormal signal shadow in the splenogastric hiatus, as shown on MRI and indicated by high signal intensity on T2-weighted imaging, required further examination to rule out lymph node metastasis of breast cancer, or a gastric mesenchymal tumor. The enhanced CT and PET-CT scans had sufficient diagnostic clarity to differentiate between the three potential diagnoses in this particular case. EUS uses grayscale imaging for analysis, a technique that facilitates the clear display of the status of lymph nodes in the vicinity of upper gastrointestinal tract tumors, and the identification of the nature of the lymph nodes based on their imaging features. The accuracy of EUS in predicting malignant lymph nodes is >80% when the intraluminal ultrasound features of the lymph nodes are hypoechoic, round, with clear borders, and >1 cm in size (22). A number of studies have shown that conventional EUS exhibits a higher degree of efficacy in detecting lymph node metastasis of upper gastrointestinal tract tumors than CT (23-25). However, other studies have reported that the diagnostic performance of conventional EUS is unsatisfactory, with significant variations in study outcomes (26,27). If the CT or MRI or PET-CT results are inconsistent, abdominal or extra-gastric wall lesions have to first be excluded, and LAEUS should then be performed to determine a diagnosis of a gastrointestinal stromal tumor or breast cancer lymph node metastasis. After excluding lesions outside the gastric wall, mini-probe EUS can be performed to further observe the size, location, and morphology of the lesion to finalize the diagnosis.

Multidisciplinary collaboration is particularly important in clinical practice. Joint diagnosis using gastroenterology and imaging is needed to avoid the limitations of a single examination and improve the clinician’s clinical multidimensional thinking.

Conclusions

This case highlights the significant diagnostic challenge of distinguishing GDs from GISTs and metastatic lesions, particularly in patients with previous malignancies. While cross-sectional imaging (CT, MRI, and PET-CT) may suggest submucosal tumors or metastasis due to overlapping features like T2 hyperintensity or soft-tissue density, these modalities lack specificity, and can lead to misdiagnosis as demonstrated by the inconsistent findings in this case. EUS, especially mini-probe technology, proved critical for the definitive diagnosis in this case, as it directly visualized the localized thinning and loss of the muscularis propria layer—pathognomonic for GD—while effectively excluding extra-gastric pathology like a GIST or lymph node metastasis. This underscores the superiority of EUS in evaluating mural integrity for ambiguous gastric lesions. Multidisciplinary collaboration among gastroenterology, radiology, and surgery teams is essential to reconcile inconsistent imaging results and guide appropriate diagnostic pathways, ultimately preventing unnecessary interventions for asymptomatic GD, and ensuring precise, resource-efficient management. EUS should be prioritized in such ambiguous cases to optimize diagnostic accuracy and prevent overtreatment.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-756/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 Medical Ethics Review Committee of The First Affiliated Hospital of Zhejiang Chinese Medical University (No. 2025-KL-411-01) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the 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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