[A Case on the Long‒Term Effect of Imatinib on GIST of Unknown Primary Origin with Multiple Liver Metastases, Peritoneal Dissemination, and Bone Metastasis].

A 61‒year‒old woman observed that she had a lower limb edema approximately 1 month ago and began to feel a general malaise. The symptom was caused by multiple liver metastases, and the primary lesion was suspected to be an ovarian cancer. Peritoneal disseminations throughout the abdominal cavity were found in the exploratory laparotomy. No obvious primary lesion could be found in the searchable gastrointestinal tract. The patient was diagnosed with a gastrointestinal stromal tumor(GIST)based on the biopsy results of the peritoneal dissemination. Treatment with imatinib mesylate(imatinib) was initiated 13 days after surgery. The severe lower extremity edema disappeared within 2 months. Computed tomography (CT)scan showed a reduction of the multiple liver metastases and peritoneal dissemination, and the appearance and increase of calcifications in the tumor and cystic degeneration inside the liver metastasis. The abnormal accumulation observed by bone scintigraphy also disappeared. Imatinib has a long‒term effect on GIST of unknown primary origin with multiple liver metastases, peritoneal dissemination, and bone metastasis. Five years after the initiation of the treatment, the patient is still alive, and new lesions have not developed.