The Accuracy of Endoscopic Ultrasound in the Assessment of Gastrointestinal Stromal Tumours and Leiomyomas - Correlation of EUS Diagnosis, Size and Malignant Potential with Surgical Pathology

Abstract

Background and Aims: Endoscopic ultrasound (EUS) is a useful tool in the assessment of submucosal lesions of the gastrointestinal tract. For gastrointestinal stromal tumours and leiomyomas (GIST/Ls), EUS plays a role in confirming origin from the muscle layer, measuring lesion size and assessing malignant potential. This series aims to evaluate the performance characteristics of EUS with regard to these factors as compared with surgical pathology. Methods: Patients receiving a diagnosis of GIST/L at EUS (defined as a localised hypoechoic expansion of muscularis mucosae or propria) were identified via interrogation of a prospective endoscopic database. Those who subsequently underwent surgical resection were selected for analysis. The EUS assessment of size and suspected malignant potential were compared with surgical pathology findings. Results: Between 1997 and 2005, 125 patients received an EUS diagnosis of GIST/L at a single tertiary institution. Of these patients, 41 subsequently underwent surgical resection. The diagnosis of GIST/L was confirmed on surgical pathology in 33 cases (80%), with alternative diagnoses of inflammatory/fibrotic mass = 4, duplication cyst = 1, infiltrating pancreatic adenocarcinoma = 1, pancreatic rest = 1, cavernous hemangioma = 1. For lesions confirmed as GIST/Ls on surgical pathology, the Pearson correlation co-efficient for correlation between size measurements at EUS and pathological examination was 0.926 (p<0.001). On the basis of defined EUS criteria [1], 17 were thought to be of high malignant potential. However surgical pathology revealed none to be of high malignant potential according to consensus pathology criteria. Conclusion: EUS has an acceptable accuracy in diagnosing GIST/Ls on the basis of endosonographic confirmation of origin from a muscularis layer. It is a highly accurate modality for measuring lesion size. However, the utility of previously proposed EUS criteria for malignant potential appears to be less reliable. 1. Chak, A., M.I. Canto, T. Rosch, et al., Endosonographic differentiation of benign and malignant stromal cell tumors. Gastrointest Endosc, 1997. 45(6):p. 468-73.