Sensitivity and Accuracy of Endoscopic Ultrasound in Diagnosing the Layer of Origin for Gastric Subepithelial Lesions

Abstract

Purpose: Gastric subepithelial lesions (GSL) are usually found incidentally by imaging or upper endoscopy. The most common etiology is gastrointestinal stromal tumors (GIST), which are pre-malignant lesions. Other etiologies include leiomyoma, leiomysarcoma, lipoma, and schwannoma. Endoscopic ultrasound (EUS) has become an important diagnostic tool by helping to assess size, tissue characteristics, and layer of origination. These factors, especially layer of origin, can implicate GIST over other diagnoses and significantly impact further management strategy by appropriately referring pre-malignant or malignant lesions to resection. The aim of this study was to evaluate the sensitivity and accuracy of EUS in discerning the layer of origin (LO) of GSL. Methods: A retrospective chart review of EUS reports, images, cytology, and surgical pathology for all patients with subepithelial lesions presenting between April 2006 and February 2010 was done at our tertiary medical center. A total of 30 patients were identified who underwent EUS followed by laparoscopic wedge resection of a GSL. EUS were performed by a single experienced endosonographer. All patients underwent standard EGD and complete examination with a linear echoendoscope. FNA was performed by making 1 to 5 passes with a 22-gauge needle, at the discretion of the endosonographer. Immunohistochemical specimens were prepared as direct smears with routine hematoxylin and eosin-stained sections. Surgical specimens from laparoscopic resection were reviewed by staff pathologists. Results: 30 patients were identified who underwent EUS followed by wedge resection of a GSL. 27 of these patients had an EUS diagnosis of a GSL arising from either the submucosa (SM) or muscularis propria (MP), which was confirmed with surgical pathology. One patient had a false positive EUS finding of a GSL arising from the MP. Two patients had EUS findings of a GSL in the deep mucosa and SM, respectively, which on pathology involved the MP. The sensitivity and accuracy of EUS for determining the layer of origin of GSL in this study was 93% and 90%, respectively. Of the 25 GSLs arising from the MP by EUS, 15 (60%) were found to be GIST, 4 (16%) leiomyomas, 3 (12%) schwannomas, 1 glomus tumor, 1 nodular sclerosed submucosal pseudotumor, and one false positive that was a leiomyoma, but did not involve the MP. The lesions ranged from 0.6 cm - 3.5 cm in size. Conclusion: Based on our findings, EUS is highly sensitive and accurate for diagnosing the layer of origin for GSL. Of the GSLs arising from the MP diagnosed by EUS, the majority were GISTs. EUS remains an important tool in the appropriate evaluation and referral of patients for possible surgical resection of GSLs.