A Case of Giant Retroperitoneal Gastrointestinal Stromal Tumor That Achieved Long-Term Recurrence Free Survival after Curative Resection

Abstract

A 66-year-old man consulted a nearby doctor with the chief complaints of upper abdomen bloating and loss of appetite. He was diagnosed as having an abdominal mass, and was referred to our hospital for detailed examination and treatment. Abdominal CT showed a huge tumor measuring 25 cm in the retroperitoneal space. Based on EUS-FNA pathological findings, the tumor was diagnosed as a gastrointestinal stromal tumor (GIST). Preoperative chemotherapy with imatinib and sequential sunitinib was started in consideration of surgical risks and preservation of the surrounding organs. The size of the tumor did not change after chemotherapy. Since reduction of the tumor seemed to be not possible, surgical intervention was selected as the treatment choice. As the tumor originated from the retroperitoneum, and was severely adherent to the pancreas body and tail, it was extirpated with the distal pancreas and the spleen. The tumor was ultimately diagnosed as extragastrointestinal GIST by histopathological examination. Imatinib was subsequently administered for three years as an adjuvant therapy. The patient is alive without any recurrence 5 years after the surgery.