Characteristics and diagnostic sensitivity of endoscopic ultrasound in lower gastrointestinal subepithelial lesions

Lower gastrointestinal subepithelial lesions (LGI SELs) are increasingly identified. However, the diagnostic performance of endoscopic ultrasound (EUS) for LGI SELs remain inadequately defined. This study aimed to characterize EUS characteristics of LGI SELs and evaluate the optimal method for tissue acquisition.

This retrospective single-center observational study included 218 patients with 244 EUS-confirmed LGI SELs from May 2011 to February 2022. Each lesion was assessed using EUS to determine its anatomical location, size, involved GI wall layer(s), echogenicity, heterogeneity, and border characteristics. The diagnostic yields and procedural outcomes of various tissue acquisition techniques were evaluated.

The majority of SELs were incidentally discovered (67%) and primarily located in the right-sided colon (45%) and rectum (37%). EUS revealed distinct imaging characteristics for each lesion type and demonstrated high sensitivity, particularly for neuroendocrine tumors (NETs) (94%) and lipomas (96%). Tissue acquisition using either endoscopic or surgical resection achieved high diagnostic yield, significantly outperforming the bite-on-bite biopsy (75%, p = 0.007). Additionally, EUS significantly improved the diagnostic sensitivity for SEL with malignant potential compared to colonoscopy alone (87.9% vs. 74.2%, p = 0.046).

EUS offers valuable characterization of LGI SELs, particularly for rectal NETs and lipomas. En bloc tissue acquisition methods, including endoscopic and surgical resection, demonstrated superior diagnostic yield compared to bite-on-bite biopsy. EUS significantly enhanced diagnostic sensitivity compared to colonoscopy alone, especially for SELs with malignant potential. These findings support the role of EUS as a complementary modality to colonoscopy in the evaluation of LGI SELs.