Gastroduodenal Intussusception With Gastric Outlet Obstruction and Periampullary Compression Due to a Gastrointestinal Stromal Tumor in the Stomach

Introduction

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, representing approximately 1% of all gastrointestinal (GI) neoplasms [1]. Predominantly arising in the stomach, these lesions often present with nonspecific symptoms such as GI bleeding or abdominal discomfort. Gastroduodenal intussusception is an exceedingly rare presentation, characterized by telescoping of the gastric wall – most often the antrum – into the duodenum. Among all forms of intussusception, this is the rarest in adults and occurs in fewer than 10% of cases; GISTs represent the most common lead point [2,3]. When associated with biliary obstruction, the clinical scenario becomes even more atypical. This report describes a gastric GIST that manifested as gastroduodenal intussusception and uniquely demonstrated functional ampullary obstruction due to external compression, evidenced by cholestatic liver function tests, a dilated common bile duct without intraluminal pathology, and biochemical pancreatitis. Such an association has not previously been documented in the Indian population.

Case Report

A 71-year-old woman presented with a 10-day history of melena, followed by multiple episodes of non-bilious vomiting containing food particles for 7 days, and generalized weakness during the same period. She had a 10-year history of hypertension; she also had experienced a cerebrovascular accident 3 months earlier and been prescribed dual antiplatelet therapy. Evaluation at another hospital had revealed severe anemia (hemoglobin 4.8 g/dL); she then received 2 units of packed red cells. Upper GI endoscopy at the other hospital showed a large submucosal polypoid lesion occupying two-thirds of the gastric antrum with surface ulceration, suggestive of a GIST (Figure 1). Endoscopic ultrasound demonstrated a 3×5 cm heteroechoic lesion arising from the second layer of the gastric wall with internal hemorrhage. At our hospital, a complete blood workup – including complete blood count, liver function tests, renal function tests, and coagulation profile – was performed. The results showed a hemoglobin level of 6.8 g/dL and an international normalized ratio of 1.07. Endoscopic submucosal dissection was initially planned but deferred because of the large mass size. Liver function tests demonstrated an obstructive pattern with elevated transaminases (serum glutamic oxaloacetic transaminase 157 IU/L, serum pyruvic oxaloacetic transaminase 149 IU/L), alkaline phosphatase (166 IU/L), gamma-glutamyl transferase (239 IU/L), and bilirubin (1.66 mg/dL). Serum amylase and lipase levels were 1294 IU/L and 2531 IU/L, respectively, consistent with acute pancreatitis. Given the deranged liver function tests and cholestatic changes, magnetic resonance cholangiopancreatography was performed. The resulting images showed mildly prominent intrahepatic biliary radicles and a dilated common bile duct (9.9 mm) without intraluminal stones; ampullary morphology was normal and a duodenal mass was evident (Figure 2).

Triple-phase computed tomography (CT), performed to assess lesion extent and assist with surgical planning, confirmed a well-defined heterogeneously enhancing mass in the pyloric antrum protruding into the duodenum and causing gastroduodenal intussusception (Figure 3). Exploratory laparotomy was conducted after initial nasogastric decompression and blood transfusion. Intraoperatively, the antrum showed intussusception into the first part of the duodenum, and the GIST served as the lead point. Manual reduction of the intussusception was performed; the pylorus and duodenum were viable. A wide-based GIST was excised with adequate margins via gastrotomy (Figure 4).

Postoperatively, the patient experienced uncomplicated recovery with early return of bowel function, tolerance of oral intake, and resolution of gastric outlet obstruction symptoms. A postoperative CT scan with oral contrast demonstrated normal passage of contrast from the stomach into the duodenum and proximal jejunal loops without evidence of leakage. She was discharged on postoperative day 7 in stable condition.

Histopathology revealed a 5.5×2.2×1.8 cm unifocal, low-grade (G1) mixed-type GIST of the gastric antrum with a mitotic rate of 3 per 50 high-power fields. Immunohistochemistry showed CD117 and Discovered On GIST-1 (DOG1) positivity, with a Ki-67 index of ~3%. The tumor was staged as pT3 (American Joint Committee on Cancer [AJCC] 8th edition) and classified as low risk (modified National Institutes of Health risk stratification criteria) (Figure 5).

Discussion

Adult intussusception represents only 5% of all intussusception cases and fewer than 1% of intestinal obstructions [4]. Gastroduodenal intussusception is the rarest subtype, present in fewer than 10% of adult cases [2]. It typically occurs due to a lead-point lesion such as a pedunculated GIST, lipoma, leiomyoma, schwannoma, polyp, or carcinoma [5]. GISTs are the most common tumors associated with gastroduodenal intussusception; they often arise from the gastric wall near the pylorus. Fewer than 50 cases have been reported, and more than half have been gastric GISTs [6]. These cases mainly occurred in older women (mean age ~64 years; range, 29–95 years) and the GISTs often were large (>4 cm), causing mechanical obstruction [7]. Clinical presentation typically includes features of gastric outlet obstruction, such as upper abdominal discomfort, pain, nausea, vomiting, anorexia, postprandial fullness, hematemesis, and melena. A few case reports have described gastroduodenal intussusception–induced pancreatitis due to GIST, as observed in our patient [8,9].

The diagnosis of gastroduodenal intussusception can be established using imaging modalities such as upper gastrointestinal endoscopy and contrast-enhanced CT [10]. On endoscopy, the lesion often appears as a mass prolapsing into the lumen, occasionally accompanied by the gastric wall. Contrast-enhanced CT is particularly valuable for assessing the extent of intussusception and delineating the tumor’s base – essential aspects surgical planning. In the present case, along with endoscopy and contrast-enhanced CT, magnetic resonance imaging was performed because of the patient’s deranged liver function tests and elevated serum amylase and lipase levels; the findings ruled out intraluminal pathology within the common bile duct.

The standard treatment for gastric GISTs, including those presenting with gastroduodenal intussusception, is complete surgical resection. Historically, this has been achieved through open surgery; however, advances in minimally invasive techniques have expanded available surgical options to include laparoscopic–endoscopic cooperative surgery [11], non-exposed endoscopic wall inversion surgery [12], and combination techniques such as CLEAN-NET (Combination of Laparoscopic and Endoscopic Approaches to Neoplasia with Non-Exposure Technique) [13]. Although these procedures offer reduced invasiveness and improved postoperative recovery, they are technically demanding and available only in select specialized centers. For older patients or those with serious comorbidities, in whom general anesthesia and operative stress pose substantial risks, resection via the endoscopic submucosal dissection technique may be considered as a minimally invasive alternative [14]. Endoscopic submucosal dissection is particularly suitable when the tumor arises from the muscularis mucosae and has a narrow base. A few case reports describe successful use of endoscopic submucosal dissection in high-risk patients who were not candidates for surgery. In general, the choice of treatment must consider the tumor’s location, size, depth of invasion, and base, as well as the patient’s overall condition and surgical risk. When feasible, endoscopic reduction of the intussusception followed by planned surgical resection may be attempted. However, for instances of complete obstruction or active bleeding, as in the present case, upfront surgical intervention remains the preferred approach. Neoadjuvant therapy with imatinib is recommended in selected cases to reduce tumor size and facilitate complete (R0) resection, particularly when adjacent organ involvement is suspected [14].

Definitive diagnosis of a GIST requires immunohistochemistry because hematoxylin and eosin staining alone is insufficient. CD117 is the primary marker, although up to 15% of GISTs may be CD117-negative, making DOG1 a useful adjunct [15]. Histologically, these tumors are classified into 3 main types: spindle cell (70%), epithelioid (20%), and mixed (10%) [16]. In the present case, the tumor was located in the gastric antrum, measured 5.5×2.2×1.8 cm, and was unifocal with mixed histology. The mitotic rate was 3 per 50 high-power fields and necrosis was absent; the tumor was classified as G1 (low grade), with low risk of aggressive behavior. The margins were clear, and no lymph nodes were submitted. The pathologic stage was pT3 (AJCC 8th edition). Immunohistochemistry showed CD117 and DOG1 positivity, confirming the diagnosis. The Ki-67 index was ~3%, indicating low proliferative activity (Table 1).

Our case is distinct from previous reports because it includes biochemical and imaging findings consistent with obstructive jaundice and pancreatitis. The mass had invaginated into the duodenum and exerted pressure on the ampulla of Vater, resulting in cholestatic liver function test patterns and a dilated common bile duct without intraluminal obstruction, as well as biochemical signs of acute pancreatitis – suggesting functional ampullary obstruction due to external compression. This case highlights the need to consider rare extrinsic ampullary compression by gastric GIST in older patients with overlapping gastric outlet obstruction, biliary compression, and pancreatic symptoms. It underscores the diagnostic value of multimodal imaging and the importance of timely, tailored surgical intervention in complex presentations.

Conclusions

Gastroduodenal intussusception represents an exceptionally rare manifestation of gastric GISTs. To our knowledge, its association with concomitant radiological and biochemical evidence of biliary obstruction and acute pancreatitis has not previously been documented. This report emphasizes the need for a high index of suspicion in older patients who present with upper gastrointestinal bleeding, signs of gastric outlet obstruction, and features suggestive of obstructive jaundice. In patients with resectable, low-risk disease, surgical resection can provide excellent outcomes.