Double contrast-enhanced ultrasonography in an exophytic gastric glomus tumor with unremarkable gastroscopy: A case report

Abstract

BACKGROUND

Gastric glomus tumors (GGT) are rare mesenchymal tumors which are difficult to diagnose accurately before surgery because their clinical, endoscopic, and imaging findings are not specific. Double contrast-enhanced ultrasonography (DCEUS) may provide useful information on gastric wall structure, tumor growth pattern, and vascular enhancement.

CASE SUMMARY

A 55-year-old woman presented with paroxysmal upper abdominal pain for 1 month. Laboratory tests showed mild anemia and several biochemical abnormalities. Routine gastroscopy revealed no remarkable findings. Contrast-enhanced computed tomography demonstrated a well-defined intramural nodule in the gastric antrum with progressive enhancement, and a neuroendocrine tumor was considered. DCEUS showed preserved gastric wall stratification and a hypoechoic ovoid lesion on the greater curvature of the gastric antrum. The lesion protruded slightly outward and showed a hypervascular enhancement pattern on DCEUS. An exophytic gastrointestinal stromal tumor was suspected preoperatively. The patient underwent laparoscopic resection. Histopathology and immunohistochemistry confirmed a GGT. She recovered uneventfully and remained recurrence-free during 2 years of follow-up.

CONCLUSION

DCEUS may be a useful complementary modality for the preoperative evaluation of small hypervascular exophytic gastric wall lesions.

Key Words: Contrast-enhanced computed tomography; Double contrast-enhanced ultrasonography; Exophytic gastric lesion; Gastroscopy; Gastric glomus tumor; Case report

Core Tip: Gastric glomus tumor is a rare gastric mesenchymal tumor and is frequently misclassified before surgery because its symptoms and imaging appearances may overlap with those of gastrointestinal stromal tumors and neuroendocrine tumors. This case shows that double contrast-enhanced ultrasonography can depict the gastric wall structure, exophytic growth pattern, and dynamic vascular enhancement of a small hypervascular antral lesion, providing useful complementary information when gastroscopy is unremarkable.

INTRODUCTION

Gastric glomus tumor (GGT) is a rare mesenchymal tumor originating from modified smooth muscle cells of the glomus body[1]. Glomus tumors most commonly occur in the extremities and gastrointestinal involvement is uncommon, and GGT account for < 1% of all gastric mesenchymal tumors[2]. They are usually located in the gastric antrum and may present with nonspecific symptoms, including abdominal pain, upper gastrointestinal bleeding, and anemia, although some cases are incidentally detected during routine examination.

Preoperative diagnosis of GGT remains challenging because its clinical, endoscopic, and radiological findings are not pathognomonic. Consequently, they are frequently misdiagnosed as other gastric subepithelial tumors, particularly gastrointestinal stromal tumors[3]. Histopathological and immunohistochemical examinations remain essential for definitive diagnosis. Here, we report a case of GGT presenting with upper abdominal discomfort and decreased hemoglobin level that was preoperatively suspected as a neuroendocrine tumor or gastrointestinal stromal tumor. We review the clinical and imaging findings of this case, with particular emphasis on the role of double contrast-enhanced ultrasonography (DCEUS) in the preoperative assessment of exophytic gastric wall lesions.

CASE PRESENTATION

Chief complaints

A 55-year-old woman was admitted with complaints of paroxysmal upper abdominal pain lasting for 1 month.

History of present illness

One month before admission, the patient developed intermittent dull upper abdominal pain without an obvious precipitating factor. The pain was more pronounced during fasting but was mild and tolerable. She denied nausea, vomiting, hematemesis, melena, or other obvious discomfort, and reported no recent changes in appetite or bowel habits.

History of past illness

The patient had an unremarkable history of past illness.

Personal and family history

The patient had no notable personal or family history.

Physical examination

Physical examination revealed mild tenderness in the middle and upper abdomen, with no other significant positive findings.

Laboratory examinations

Laboratory tests revealed multiple abnormalities. The white blood cell count was mildly decreased to 3.4 × 10⁹/L (reference range: 3.5 × 10⁹-9.5 × 10⁹/L). Hemoglobin was slightly reduced to 106 g/L (reference range: 115-150 g/L), and the lymphocyte count was below normal at 0.9 × 10⁹/L (reference range: 1.1 × 10⁹-3.2 × 10⁹/L). Liver function tests showed mildly elevated alanine aminotransferase and aspartate aminotransferase levels of 67 U/L and 78 U/L, respectively (reference ranges: 7-40 U/L and 13-35 U/L), with an increased alkaline phosphatase level of 214 U/L (reference range: 35-100 U/L). Serum albumin was decreased to 35.2 g/L (reference range: 40-55 g/L). Immunological testing revealed an elevated rheumatoid factor of 39.2 IU/mL (reference range: < 14 IU/mL), and IgA, IgM, and IgG were mildly increased to 4.1 g/L, 2.6 g/L, and 26.3 g/L, respectively (reference ranges: 0.6-3.3 g/L, 0.5-2.3 g/L, and 7.0-16.0 g/L). All other laboratory parameters were within normal limits.

Imaging examinations

Upper gastrointestinal endoscopy showed no remarkable abnormalities. Contrast-enhanced computed tomography (CT) demonstrated a well-defined intramural nodule in the gastric antrum, measuring approximately 14 mm × 9 mm, with relatively clear margins and progressive enhancement; a neuroendocrine tumor was considered radiologically (Figure 1A and B). DCEUS revealed preserved gastric wall stratification, slightly rough mucosa, and a hypoechoic ovoid lesion measuring approximately 13 mm × 8 mm on the greater curvature of the gastric antrum. The lesion protruded slightly outward, had a smooth surface, and showed abundant internal blood flow signals (Figure 1C and D). On dynamic contrast-enhanced imaging, the lesion exhibited rapid hyperenhancement beginning at 8 seconds, reaching a peak at approximately 14 seconds with a peak intensity of -32.4 dB, which was higher than that of the adjacent gastric wall (-44.8 dB), followed by slight washout while remaining hyperenhanced in the delayed phase (Figure 1E). Based on these findings, an exophytic gastrointestinal stromal tumor was considered. Because contrast-enhanced CT and DCEUS had already provided sufficient information regarding lesion location and imaging characteristics for surgical evaluation, additional endoscopic ultrasonography (EUS) examination was not performed in the initial diagnostic workup.

Figure 1 Imaging findings of the gastric glomus tumor. A and B: Contrast-enhanced computed tomography showed a well-defined enhancing nodule in the gastric antrum on axial and sagittal images (arrows; scale bar: 5 cm); C: Double contrast-enhanced ultrasonography demonstrated a hypoechoic ovoid lesion on the greater curvature of the gastric antrum, slightly protruding outward; D: Color Doppler ultrasonography revealed abundant intralesional blood flow signals (arrow; scale bar: 5 mm); E: Contrast-enhanced ultrasonography and the corresponding time–intensity curve demonstrated earlier and stronger enhancement of the lesion than the adjacent gastric wall, followed by slight washout while remaining hyperenhanced in the delayed phase.

FINAL DIAGNOSIS

Histopathological examination of the resected lesion showed nests and sheets of uniform round tumor cells arranged around branching and dilated vascular channels (Figure 2A). Immunohistochemical staining revealed diffuse positivity for smooth muscle actin (Figure 2B), whereas CD117, DOG-1, CD34, vimentin, S-100, desmin, CD56, chromogranin A, synaptophysin, cytokeratin (pan), and p53 were negative. CD34 positivity was observed only in vascular structures, and the Ki-67 proliferation index was low, approximately 2%. These findings supported the final pathological diagnosis of GGT.

Figure 2 Surgical and pathological findings of the gastric glomus tumor. A: Hematoxylin and eosin staining showed nests and sheets of relatively uniform round tumor cells arranged around dilated vascular channels (arrows; scale bar: 100 μm); B: Immunohistochemical staining demonstrated positive expression of smooth muscle actin in the tumor cells; C: Intraoperative laparoscopic view revealed a protruding mass on the gastric wall; D: Gross appearance of the resected specimen showed a well-circumscribed nodular lesion.

TREATMENT

The patient underwent laparoscopic resection of the gastric mass (Figure 2C and D).

OUTCOME AND FOLLOW-UP

Postoperative recovery was uneventful, with no significant complications or sequelae. During the 2-year follow-up, the patient remained well, with no evidence of recurrence or metastasis.

DISCUSSION

GGT is a rare mesenchymal neoplasm. Although most cases are considered indolent and have a favorable prognosis, malignant behavior and distant metastasis have been documented. Deng et al[4] reported that one of 15 patients with GGT developed postoperative liver metastasis. Next-generation sequencing identified EGFR, PIK3CA, KEAP1, and TP53 mutations in individual cases, suggesting that the biological behavior and molecular features of GGT are more heterogeneous than previously appreciated[4]. Therefore, improving awareness of GGT and its clinicopathological characteristics remains clinically important.

Clinically, GGT often lack specific manifestations. Many cases are incidentally detected during routine examinations, whereas others present with gastrointestinal bleeding, including hematemesis, melena, anemia, or even recurrent or acute upper gastrointestinal hemorrhage in severe cases[5,6]. Nonspecific symptoms such as upper abdominal pain and dyspepsia have also been reported[7,8]. Although overt gastrointestinal bleeding was not observed in the present case, the patient had mild anemia and upper abdominal pain, which may have been related to the GGT. However, other laboratory abnormalities, including leukopenia, lymphopenia, elevated liver enzymes, hypoalbuminemia, and abnormal immunological markers, are not typical manifestations of GGT, and their exact causes could not be determined based on the available clinical information.

Existing imaging techniques can provide useful diagnostic clues, but each has inherent limitations. EUS is highly useful for evaluating the echogenicity and layer of origin of gastric wall lesions; however, for lesions with an exophytic outward growth pattern, it may have limitations in lesion localization and in fully delineating the extraluminal component[9]. CT can provide a global view of the lesion and surrounding structures, but when gastric distension is insufficient, accurate assessment of small antral wall lesions may be challenging. In addition, CT has limited ability to display the detailed layered structure of the gastric wall, and CT findings alone are often insufficient for a definitive preoperative diagnosis[10]. EUS-guided fine-needle aspiration can facilitate preoperative diagnosis when adequate cytological or histological specimens are obtained for immunohistochemical assessment, but it may also be associated with complications such as bleeding[11]. Against this background, DCEUS may serve as a valuable complementary tool for the assessment of gastric wall lesions. This technique combines oral gastric contrast, which distends the gastric lumen and delineates the layered structure of the gastric wall, with intravenous microbubble CEUS, which enables real-time evaluation of lesion perfusion. Transabdominal scanning of the distended stomach also provides a broader view of the lesion contour and extraluminal border, which may be useful for detecting small lesions with an exophytic outward growth pattern. In addition, intravenous microbubble CEUS enables real-time evaluation of microvascular perfusion, including enhancement intensity, homogeneity, persistence, and washout pattern. Therefore, the core advantage of DCEUS lies in its ability to integrate wall-layer assessment, growth pattern characterization, and dynamic vascular evaluation in the preoperative assessment of small gastric antral lesions. Previous studies have suggested that DCEUS may provide diagnostic performance comparable to that of EUS in selected patients with gastric stromal tumors[12]. Nevertheless, DCEUS has inherent limitations. Its diagnostic performance depends on adequate gastric filling and a satisfactory acoustic window, and lesion visualization may be affected by bowel gas, body habitus, operator experience, posterior gastric wall location, or a deep lesion position relative to the abdominal probe.

Because the clinical and imaging manifestations of GGT overlap substantially with those of other gastric subepithelial tumors, particularly gastrointestinal stromal tumors and neuroendocrine tumors, accurate preoperative diagnosis remains challenging, with a previously reported diagnostic accuracy of only 33.3% (5/15)[4,13]. In the present case, contrast-enhanced CT suggested a neuroendocrine tumor, whereas DCEUS favored a gastrointestinal stromal tumor. This discrepancy may be explained by the shared imaging features of these lesions, as small GGT, gastrointestinal stromal tumors, and neuroendocrine tumors can all present as well-defined gastric wall or subepithelial lesions with hypervascular enhancement. Nevertheless, several imaging clues may help refine the differential diagnosis[14,15]. GGT typically occur in the gastric antrum and appear as well-defined subepithelial lesions, often arising from the submucosa or muscularis propria. Their characteristic imaging feature is marked, relatively homogeneous, and persistent enhancement, reflecting their rich vascularity. Gastric gastrointestinal stromal tumors can occur throughout the stomach, more often in the body or fundus, and usually originate from the muscularis propria; larger lesions may show exophytic growth, heterogeneous enhancement, necrosis, hemorrhage, or cystic degeneration. Gastric neuroendocrine tumors are often located in the gastric body or fundus and commonly present as small hypervascular mucosal or submucosal polypoid lesions.

Another noteworthy feature of the present case was the slight exophytic growth pattern. Most reported GGT are described as gastric antral subepithelial or intramural lesions, often presenting as mucosal or submucosal protrusions on gastroscopy or EUS[16,17]. In contrast, conventional gastroscopy in the present case showed no remarkable abnormality, whereas DCEUS demonstrated a small lesion arising from the gastric antral wall with slight outward protrusion. This finding may partly explain the negative gastroscopic result and highlights the value of DCEUS in assessing the relationship between small gastric wall lesions and the surrounding gastric wall. The exophytic growth pattern, together with preoperative diagnostic uncertainty, also influenced the therapeutic strategy. Although endoscopic minimally invasive techniques, such as endoscopic submucosal dissection and submucosal tunneling endoscopic resection, are feasible for selected gastric subepithelial tumors, their suitability depends on lesion accessibility and the feasibility of complete and safe resection. In the present case, gastrointestinal stromal tumor or neuroendocrine tumor could not be excluded preoperatively, and laparoscopic resection was therefore selected to ensure complete removal and obtain a definitive pathological diagnosis.

CONCLUSION

This case highlights that GGT should be considered in the differential diagnosis of small hypervascular gastric wall lesions, and that DCEUS may serve as a useful complementary modality for their preoperative evaluation.

ACKNOWLEDGEMENTS

We would like to express our sincere gratitude to the medical staff Nanxun People’s Hospital for their assistance. Without their efforts in interprofessional collaboration for data collection and patient treatment, this case report would not have been possible.