Abstract
Endoscopic ultrasonography (EUS) was performed on 19 cases with gastric leiomyoma and on 8 cases with gastric leiomyosarcoma. We tried to determine whether EUS images could serve to distinguish leiomyosarcoma from leiomyoma. Ultrasonographic equipments used were OLYMPUS GF-UM1, GF-UM2 and GF-UM3 at the frequencies of 7.5 or 10 or 12MHz, with water fill-up method. The mean of the maximum diameter of leiomyoma was 3.9±1.9 cm (mean ± SD) and that of leiomyosarcoma was 9.9 ± 5.9 cm, the difference being significant (p <0.0005). We classified the tumors into three groups based on the tumor sizes : less than 3cm, 3-8.9 cm and more than 9cm in diameter and compared each other to determine whether leiomyoma or leiomyosarcoma has characteristic EUS images. In 7 tumors less than 3cm in diameter, 6 tumors were leiomyomas whose EUS images were characterised by smooth marginal echoes and homogeneous internal echo textures without cystic formation more than lcm in diameter. Four tumors were more than 9cm in diameter and all of them were leiomyosarcomas with cystic formation more than lcm in diameter. Sixteen tumors in the range of 3 to 8.9 cm in diameter were often difficult to distinguish malignant from benign tumors and the accuracy remained arround 60% level based on EUS images. For this reason, histologic examinations of biopsy specimens are required for this group of tumors. In conclusion, the tumors smaller than 3cm or larger than 9cm in diamer are rather accurately differentiated as benign or malignant based on EUS images, but the tumors with intermediate in size, from 3 to 8.9 cm, are often difficult to distinguish malignant from benign fumors based on the sonographic characteristics alone.
