Abstract
We experienced two cases of gastrointestinal stromal tumor (GIST) with definite growth. Both tumors showed a homogeneous internal echogenecity. EUS-guided aspiration needle biopsy revealed few mitotic figures and leiomyoma was diagnosed by H-E stain. Because both tumors showing growth, partial gastrectomy was performed via laparoscopy. Histopathological examination yielded a diagnosis of GIST (uncommitted type) using stain for c-kit and other immunohistochemical markers. Since 1-2 mitotic figures were seen per 10 HPF, malignancy was suggested. Therefore, it is necessary to give careful consideration to malignancy if the tumor is growing more than 7 to 8 mm per one year, even though there is little evidence of a malignant lesion on EUS or biopsy. Also, biopsy tissue should be examined using immunohistochemical stain to diagnose GIST. Even if there are few mitotic figures, consideration must be given to the degree of biological malignancy of GIST when evaluating the indications for surgery.
