Endoscopic ultrasonography (EUS) is a useful imaging procedure for the diagnosis of submucosal tumors in the stomach. The present study investigated the EUS features of benign and malignant gastrointestinal stromal tumors (GISTs) and assessed differences between the two groups.

Thirty patients with a GIST in the stomach were included in the study (23 benign and 7 malignant GISTs). We compared characteristic EUS findings (tumor size, location of tumor, regularity of the outer margin, echo-heterogeneity, presence of cystic spaces, echogenic foci and mucosal ulceration) between benign and malignant GISTs.

Tumor sizes over 40 mm were observed in 85.7% of the malignant and 8.7% of the benign tumors (P=0.000). Intralesional cystic spaces were noted in 71.4% of the malignant and 8.7% of the benign tumors (P=0.003). The outer margin was irregular in 71.4% of the malignant and 8.7% of the benign tumors (P=0.014). 85.7% of the malignant and 13.0% of the benign tumors had an echo-heterogeneity in the tumor (P=0.001). The locations of tumor and the presence of echogenic foci or mucosal ulcerations were not different between the two groups.

Tumor sizes over 40 mm, intralesional cystic spaces, irregular outer margins, and echo-heterogeneity in the tumor were significantly more frequent in malignant GISTs. EUS can provide informations in differentiating benign from malignant GISTs.