Abstract
A 69-year-old woman was referred to our hospital because of appetite loss and a palpable abdominal tumor. Imaging diagnostic methods revealed a well demarcated tumor with the heterogeneous center part in the right upper quadrant of abdomen. Gastrointestinal stromal tumor (GIST) was suspected and the patient was operated on. At surgery we identified a 15-cm diameter tumor in the subserosal structure at the lesser curvature of the stomach, and performed partial gastrectomy. Pathological findings primarily suggested GIST on hematoxylin/eosin staining. Immunohistochemistry, however, showed that the tumor was KIT (-) and CD34 (+), and did not harbor c-kit gene mutation and platelet-derived growth factor receptor α (PDGFRA) gene mutation. Finally c-kit gene mutation negative and PDGFRA gene mutation negative, high risk GIST was diagnosed. Adjuvant chemotherapy was considered, but imatinib has not been administered because no gene mutations are seen and her clinical course is under observation.
