[A Case of GIST with Extensive Peritoneal Dissemination Controlled over Long-Term by Low-Dose, Intermittent Administration of Imatinib after Weight Loss Surgery].

A 67-year-old man presented with abdominal pain and fever. Many abdominal tumors were detected by enhanced computed tomography(CT). The largest tumor, measuring 20 cm, had perforated the ileum and formed an abscess. Emergency surgery was performed to remove multiple tumors in the peritoneal cavity as much as possible. Immunostaining showed c-kit and CD34 positivity, and the tumors were diagnosed as gastrointestinal stromal tumor(GIST). During postoperative imatinib therapy for the residual tumor, low-dose intermittent administration was required due to side effects, but the disease was controlled for over 91months. For advanced GIST with peritoneal dissemination, 200mg/day imatinib or intermittent administration after volume reduction surgery might be effective depending on the patient's general condition.