Abstract
We report a patient with a huge and high-risk gastrointestinal stromal tumor (GIST) of the rectum treated with imatinib mesylate followed by laparoscopic intersphincteric resection. A 43-year-old man presented with difficulty in defecation and melena lasting for 2 months. Colonoscopy revealed a submucosal tumor in the anterior wall of the lower rectum, and computed tomography showed the solid mass measuring 90 mm in diameter which compressed the prostate and rectum. On digital examination, a protruding tumor was palpated at the anterior wall of the rectum, about 3 cm proximal to the anal verge. Transrectal needle biopsy revealed proliferation of spindle cells arranged in fusiform fashion which was positive for c-kit and CD34 immunostaining, indicating GIST of the rectum. Because the tumor was large that might demand difficulties in performing surgery and the patient hoped to preserve the anus, neoadjuvant treatment with imatinib mesylate was performed for six months. When the tumor was confirmed to decrease to 45 mm in diameter, he underwent laparoscopy-assisted intersphinteric resection with partial resection of the prostate. The present case suggests that neoadjuvant therapy with imatinib mesylate is useful for large rectal GISTs from the standpoint of preservation of the anal function and less invasive surgery.
