Clinical Impact of Endoscopic Ultrasound in the Evaluation of Subepithelial Lesions of the Lower Gastrointestinal Tract: 10-Year, Single-Center Experience

Abstract

Introduction: Endoscopic ultrasound (EUS) is the most accurate imaging method for evaluation of subepithelial lesions (SELs) of the gastrointestinal (GI) tract. However, reports on the use of EUS in SELs of the lower GI tract are currently limited. We aim to analyze the utility of EUS and its role in the management of lower GI SELs. Methods: Records of all patients who were referred for lower EUS evaluation of a SEL at a tertiary center between 2007 and 2018 were retrospectively reviewed after IRB approval. Data collection included patient and lesion characteristics, technical details of the procedure as well as pathology results and follow-up if available. Lesions were further subcategorized according to their size, location and final diagnosis. Results: A total of 53 patients underwent 57 EUS exams for the evaluation of a suspected SEL in the lower GI tract. Most patients were referred for EUS examinations because of abnormal findings on other imaging methods (64%). The lesions were located most frequently in the rectum (48%), followed by sigmoid (21%), cecum (10.5%) and transverse colon (9%). A statistically significant correlation between gender and location of SELs was found, with lesions located in the rectum being more frequent in women (p=0.04). The main characteristics of the SELs detected on EUS are summarized in Table 1. EUS scope (linear or radial) was used in 44 cases while EUS miniprobe was used in 13 cases. In 13 patients (22.8%), no lesion could be identified by EUS. In 2 of these cases the final diagnosis was low grade neuroendocrine tumor, and the lesion was seen on endoscopy but the size was too small to be detected on EUS. Twenty-two EUS-guided fine needle aspirations and 8 EUS-core biopsies were performed, with only 3 non-diagnostic samples and 95.3% of the remaining samples confirming the presumptive diagnosis (Figure 1). All the lesions that were samples were 1 cm or larger. None of the patients developed any complications related to the EUS procedure.505 Figure 1. 33-year-old male with perirectal mass of unknown etiology identified during workup of tenesmus A. Endoscopic findings: A subepithelial non-obstructing large mass (5cm in length) was found in the distal rectum. B. Endosonographic findings: A heterogenous (hypoechoic and hyperechoic), well-defined mass was found in the right-lateral perirectal space. It appeared to be contiguous with the muscularis propria suggesting that it is arising from the muscularis propria or is invading it. C. Elastography: Quality assessment indicated an overall hard tumor, highly suggestive of malignancy D. Fine needle aspiration for cytology was performed. Three passes were made with the 22 gauge needle using a transrectal approach. Fine needle biopsy was also performed. Two passes were made with the 20 gauge ProCore biopsy needle using a transrectal approach. Pathology results: cytology- smears showed tumor cells with oval nuclei and scant cytoplasm and sclerotic stroma; core biopsy-solitary fibrous tumor (IHC: tumor cells positive for STAT6 with patchy positivity for CD34).Conclusion: To the best of our knowledge, this is the largest cohort study regarding the clinical impact of EUS in the evaluation of SELs in the lower GI tract. EUS is a safe and accurate method as it provides valuable information regarding the location of the lesions (intramural or extramural), echogenic characteristics and their malignant potential. EUS-guided fine needle aspiration or core biopsies are feasible and safe and can be used to obtain tissue from SELs located deeper to the mucosa with a high diagnostic accuracy.