EUS DIAGNOSIS AND NATURAL COURSE OF SUBEPITHELIAL TUMORS IN THE UPPER GI TRACT - DATA FROM A TERTIARY REFERRAL CENTER

Aims Subepithelial tumors (SET) are found in 1-2% of upper endoscopies. Usually, endoscopic ultrasound (EUS) is performed as the next diagnostic step in order to determine the layer from which the SET arises and to describe the EUS features. Data from large tertiary centers on the diagnostic value of EUS and the natural course of SET are scarce.

Methods We retrospectively analyzed data from 198 patients (female: male 48,5%: 51,5%; mean age 61.7 years, range 27 - 89) referred to our center for EUS evaluation of SET of the upper GI tract between 01/01/2013 and 15/06/2019. Endoscopy databank was searched for different key words in order to extract all EUS reports with SET.

Results The mean size of SET was 17.7mm (range 3.0 - 80.0mm) and they were localized in the esophagus (n=23; 11.6%), stomach (n=137; 69. 2%) and duodenum (n=38; 19.2%). Histological diagnosis was obtained in 59 patients. GIST were the most frequent SET (50.8%) followed by leiomyoma (13.6%) and neuroendocrine tumors (NET; 11.9%), heterotopic pancreas (8.5%), lipoma (3.4%), brunneroma (3.4%), lymphoma (1.7%) and bronchogenic cyst (1.7%). GIST of the stomach had more likely an inhomogeneous echotexture (OR 5.5), contact to the proper muscle layer (OR 22.5) and a location in the gastric corpus (OR 4.2). The mean tumor growth in the population was 0.73mm a year. Malignant SET were diagnosed in 36 patients (18.2%) and sensitivity, specificity, NPV and PPV of EUS diagnosing malignant SET were 100%, 47.6%, 100% and 76.6%, respectively.

Conclusions EUS is an important diagnostic measure to differentiate benign from malignant SET. All malignant SET could be identified by EUS in our series and sent for definite treatment. Location in the gastric corpus, inhomogeneous echotexture and contact to the proper muscle layer were significantly associated with GIST diagnosis.