Incidental Gastric and Omental Gastrointestinal Stromal Tumors During One Anastomosis Gastric Bypass, A Case Report and Literature Review

Abstract

ABSTRACT

Research shows that the incidence of gastrointestinal stromal tumors (GIST) is significantly higher in patients with obesity, ranging from 0.6% to 0.8%, compared to just 0.001% in the general population. We present a case of a 53‐year‐old woman with a BMI of 47 kg/m² who planned to undergo an OAGB. During the surgery, after a primary abdominal exploration, two incidental mass lesions were found on the gastric serosa and omentum; histopathological evaluation indicated a very low‐risk GIST.

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Summary

• Individuals with elevated BMI are at increased risk for GIST development compared to those with normal BMI.
• This emphasizes the importance of considering GISTs in the differential diagnosis of patients undergoing MBS, especially in those with atypical presentations or incidental findings.

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Introduction

The one anastomosis gastric bypass (OAGB) has emerged as the third most prevalent primary bariatric and metabolic surgery (MBS) worldwide, with a significant increase in its utilization observed in recent years [1]. OAGB has established itself as an accepted standard procedure within the field of MBS [2, 3]. An increasing body of research has demonstrated favorable and enduring outcomes regarding weight loss and the resolution of comorbidities associated with this procedure [4].

Gastrointestinal stromal tumors (GISTs) represent the most prevalent type of mesenchymal tumors found in the gastrointestinal (GI) tract, with a predominant occurrence in the stomach and small intestine [5]. These tumors are typically solitary and are observed with a marginally higher frequency in males compared to females, particularly in individuals of middle to advanced age [6]. GISTs have been detected during MBS, with research indicating that their incidence is notably higher in obese patients undergoing such surgeries (0.6%–0.8%) compared to the general population (0.001%) [7–9]. With the rising frequency of MBS, there has been an increase in incidental findings, including GISTs, gastric polyps, and adenocarcinomas. These findings may alter the primary objective of the surgery, focusing on improving the patient's surgical outcomes [10].

In this report, we present a rare case of omental GIST diagnosis during an OAGB, discussing its diagnostic and therapeutic aspects.

Case History

Presentation

A 53-year-old woman with a history of morbid obesity weighs 115 kg and has a body mass index (BMI) of 47 kg/m². She follows a high-sugar, high-fat diet but does not have any obesity-related comorbidities. She has planned to undergo an OAGB. All standard pre-operative evaluations have been completed. Her upper endoscopy was normal, showing no signs of esophagitis, gastritis, or Helicobacter pylori infection.

Surgical Procedure

During the surgery, and after primary abdominal exploration, two incidental mass lesions were discovered: one on the gastric serosa and another in the omentum. (Figure 1) Both of them were excised and submitted for histopathological analysis. The OAGB procedure was performed using a standard method with a 180 cm biliopancreatic limb, and the entire procedure was completed without any complications.

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Postoperative Follow Up

The next day, an upper GI series with gastrografin was performed, which was normal. The patient was discharged from the hospital after following a clear liquid diet and establishing regular bowel habits in good condition.

Histopathology

The gastric (0.7 × 0.5 × 0.5 cm) and omental (2 × 0.5 × 0.2 cm) lesions indicated spindle cells with no mitotic activity and no atypia consistent with GIST (Risk category: very low risk).

Discussion and Conclusion

GISTs are the most common malignant tumors found beneath the lining of the GI system. These tumors are thought to originate from the interstitial cells of Cajal, which control the movement of the GI tract [11, 12]. GIST development is primarily driven by genetic mutations affecting the platelet-derived growth factor receptor (PDGFR) and/or the KIT receptor tyrosine kinase [13]. A significant percentage (10%–30%) of GISTs exhibit a cancerous progression [11, 14, 15]. It should be mentioned that studies suggest that patients with obesity have a higher incidence of GISTs (0.6%–0.8%) compared to the general population (0.0006%–0.0015%) [7–9].

GISTs are challenging to diagnose, and upper GI endoscopy is often not effective in detecting them [16]. This diagnostic difficulty is further complicated by the nonspecific clinical symptoms associated with GISTs; they can be asymptomatic or may present with vague issues such as abdominal discomfort or nonspecific bleeding [17]. Recent studies indicate that advanced imaging techniques, such as contrast-enhanced CT scans and endoscopic ultrasound with fine-needle aspiration, are more effective for early detection. However, these methods are not universally reliable when used in a preoperative setting [18, 19]. This emphasizes the importance of considering GISTs in the differential diagnosis of patients undergoing MBS, especially in those with atypical presentations or incidental findings [20–22]. This case highlights the necessity of routine vigilance for GISTs even in patients with no apparent symptoms.

Emerging evidence highlights the potential link between BMI and GIST incidence. Studies indicate that individuals with elevated BMI are at increased risk for GIST development compared to those with normal BMI. This correlation could stem from the chronic low-grade inflammation and metabolic changes associated with obesity, which may activate cancer-related pathways. Furthermore, obesity may influence tumor biology by altering the tumor microenvironment, including angiogenesis and immune response [23–25].

A GIST's prognosis depends heavily on several factors: its size, how quickly its cells are dividing, its location, and whether it has spread to other parts of the body. Diagnosis usually involves imaging, such as contrast-enhanced CT scans to determine tumor size and location. Endoscopic ultrasound with fine-needle aspiration may also be used to obtain tissue samples for analysis [26].

Surgery is the initial treatment for patients with primary GISTs that can be surgically removed. The goal is complete removal without breaking the tumor's outer layer. Laparoscopic surgery has shown excellent results, with high long-term survival rates (up to 92%) even in patients with gastric GISTs ranging in size from 1 to 10 cm. Several surgical techniques exist for removing subepithelial stomach tumors, including wedge resection, subtotal gastrectomy, distal gastrectomy, and central gastrectomy [18].

Author Contributions

Mohammad Javad Ghamari: conceptualization, project administration, writing – review and editing. Ahmadreza Sobhani: data curation, investigation, writing – original draft. Narges Mesbah: data curation, investigation, writing – original draft. Peyman Bastani: data curation, investigation, writing – original draft. Kourosh Amirian Shayesteh: data curation, investigation, writing – original draft.

Consent

The patient's written consent was obtained for the publication of this case report.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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