Potential Utility of EUS in the Diagnosis and Management of Intramural Gastric Abscess

Intramural gastric abscess is a rare phenomenon that can present as a focal intramural mass^1–13 or can occupy the entire stomach, leading to diffuse suppurative gastritis.^14,15 The bactericidal effect of gastric acid is partially responsible for the rarity of this condition.² Pathogenic mechanisms include direct invasion by microorganisms secondary to gastric mucosal trauma from foreign body ingestion,^3–5 endoscopic biopsy or polypectomy,⁶ ulcer, carcinoma, leiomyosarcoma,⁷ or empyema of the gallbladder.⁸ Alternatively, hematogenous seeding may result from pneumonia, endocarditis, impetigo, scarlet fever, typhoid fever, osteomyelitis, or erysipelas.⁹ Tis condition can also develop in the absence of any identifiable risk factors, as shown by the case reported by Khan and colleagues.¹⁶ Although Streptococcus is most often associated with this condition, a variety of aerobic and anaerobic bacteria, as well as various fungi (eg, Candida glabrata), have been implicated.

As highlighted in the case presented by Khan and coworkers, the diagnosis of suppurative gastritis may be delayed in patients presenting with prolonged epigastric pain without fever or systemic signs of infection. Abdominal computed tomography often fails to reliably differentiate an intramural abscess from a malignancy,^10,11 as illustrated in the patient treated by Khan and associates. Endoscopic ultrasound (EUS) is a valuable diagnostic tool for evaluating intramural gastric subepithelial mass lesions that offers therapeutic potential. EUS accurately discerns the layer of origin within various gastric wall layers, mass size, echo-density, echo-pattern, and relationship to adjacent structures. The differential diagnosis of gastric subepithelial masses is broad and includes both neoplastic and nonneoplastic lesions such as, but not limited to, gastrointestinal stromal tumor (GIST), lipoma, granular cell tumor, glomus tumor, pancreatic rest, carcinoids, neurofibroma, hematoma, metastatic deposits, and intramural varices.¹² The diagnosis is usually suspected based upon the presence of distinctive sonographic features with the addition of EUS-guided fine-needle aspirate (FNA) and core biopsy, which often allow definitive diagnosis. Given the rarity of gastric abscess, the typical sonographic features and potential spectrum of findings has not been sufficiently elucidated. However, the findings generally note a hypoechoic subepithelial mass with variable echogenicity^10,11 containing fluid, echogenic debris, or a foreign body, as evidenced in the case presented by Khan and colleagues. Kang and coworkers found that an increased Doppler signal at the perimeter of gastric abscesses aids in their differentiation from other sub-epithelial masses (eg, GISTs), which typically demonstrate enhanced Doppler flow within the center of the lesion.¹³ EUS-FNA often facilitates diagnosis and allows fluid aspiration and analysis to guide the administration of antibiotics.

Definitive treatment should be initiated promptly to help alleviate the risk of mortality, which has been reported to be between 37% and 92%.¹¹ Surgery, either resection or drainage, is the standard method of therapy. Alternatively, percutaneous or endoscopic drainage combined with antibiotics provides a less invasive alternative to surgery.¹ Surgical management is preferred when the presence of underlying malignancy or clinical evidence of peritonitis is uncertain or following failed efforts at non-surgical (endoscopic or percutaneous) drainage.

In conclusion, a gastric wall abscess is a rare clinical entity. In the absence of specific clinical symptoms, the diagnosis is often delayed. Even though there is a lack of pathognomonic features, the endosonographic appearance often provides important clues to the diagnosis and aids in the exclusion of other pathologies. EUS may also be utilized in a therapeutic capacity to guide antibiotic selection for fluid aspiration.