[Curative resection for bulky gastrointestinal stromal tumor with conversion therapy by imatinib]

Imatinib is a standard treatment for unresectable gastrointestinal stromal tumor (GIST). We described the case of a 66- year-old woman with bulky GIST of which a diameter was 25 cm. Therefore, we decided the tumor was unresectable. After 2-year administration of imatinib, the diameter of tumor was reduced to 6 cm. After 3-year administration of imatinib, the diameter of tumor was increased to 8 cm. The patient did not have any distant metastasis. He underwent a resection of the tumor. The historical examination showed that c-kit and CD34 were positive. The number of mitosis was 12/50 HPF. Conversion chemotherapy for bulky GIST may contribute to a curative resection.