Gastric volvulus associated with shrinkage of a gastrointestinal stromal tumor by neoadjuvant imatinib: a case report

BACKGROUND: During neoadjuvant chemotherapy for giant gastrointestinal stromal tumors, changes in gastrointestinal stromal tumor size are rarely associated with events such as perforation and bleeding that require emergency surgery. Moreover, it is very rare for gastrointestinal stromal tumors to shrink and become mobile, resulting in gastric volvulus. Herein, we report a case of gastrointestinal stromal tumor shrinkage during neoadjuvant imatinib treatment, resulting in gastric volvulus that required surgery. To the best of our knowledge, this is the first reported occurrence of gastric volvulus during neoadjuvant imatinib treatment for a giant gastrointestinal stromal tumor. CASE PRESENTATION: A 58-year-old Japanese woman who was diagnosed with a giant gastric gastrointestinal stromal tumor and administered neoadjuvant imatinib presented to our hospital with complaints of abdominal pain and retching. Enhanced computed tomography revealed that the gastrointestinal stromal tumor had shrunk and shifted in position, and the stomach had organoaxially twisted. Accordingly, the patient was diagnosed with gastric volvulus caused by a gastric gastrointestinal stromal tumor. Conservative treatment did not improve the volvulus; hence, laparotomy was performed. The tumor developed from the lesser curvature of the stomach and caused rotation of the gastric body. The local gastric wall was resected. Histopathological examination confirmed the diagnosis of gastrointestinal stromal tumor. The patient received adjuvant imatinib for 3 years and has been alive for 5 years without recurrence. CONCLUSIONS: Gastric volvulus can be caused by the laxity of the ligaments that hold the stomach and gastric ptosis or esophageal hernia and diaphragmatic hernia; therefore, gastric gastrointestinal stromal tumors rarely cause gastric volvulus. However, a risk of torsion exists if the gastrointestinal stromal tumor develops extramural to lesser curvature and attains a certain size.