A Case of Sigmoid Colon Carcinoma Associated with GIST of the Lesser Omentum Simultaneouly Resected under Laparoscopy

Abstract

A 71-year-old man presented with a tumor in the left lower quadrant of abdomen was diagnosed with sigmoid colon cancer, and he was also pointed out having a 47-mm tumor at the lesser curvature of the stomach by a CT scan for the purpose of close exploration. Gastrointestinal stromal tumor (GIST) of the stomach was suspected and laparoscopic sigmoidectomy and tumor extirpation were performed. The tumor was situated between the left gastric artery and the lesser curvature of the stomach, and no contract with the gastric wall was seen. Histopathologically the tumor was composed of irregularly arranged and proliferated spindle-shaped cells. Immunohistostaining revealed the tumor cells to be positive for c-kit and CD34 and negative for S-100 protein and αSMA. The mitotic count was less than 5 per 50 high power fields. The Ki-67 positive rate was 2 - 3 %. From these findings, it was diagnosed as GIST of the lesser omentum in the low-risk group in accordance with the modified Fletcher classification. His postoperative course was uneventful. Following adjuvant chemotherapy for sigmoid colon carcer, he has been followed in our clinic. Although extragastrointestinal GISTs are rare, we need select appropriate operative procedures by baring a possible recurrence of GIST in mind in performing surgery.