Abstract
A 40-year-old man was found to have a mass in the abdominal cavity on ultrasound. Abdominal CT scan showed a mass with a solid and a cystic compartment located in the right upper epigastrium. He was observed for three months. At this point in time he developed gastromegaly ; the mass had moved to the left upper epigastrium and had increased in size based on abdominal CT scan images. Surgery was scheduled. Prior to surgery the gastromegaly disappeared, and the patient became anemic. A rupture of a tumor was since on abdominal CT scan the tumor had decreased in size, and hemoperitoneum was present. Intraoperative findings included hemorrhagic ascites and a pedunculated cystic mass which arose from the lesser omentum ; the tumor was removed. On pathology, a gastrointestinal stromal tumor (GIST) of the lesser omentum that was positive for KIT and CD34 was diagnosed. Adjuvant therapy was not given despite the diagnosis of malignant GIST due to the presence of hemoperitoneum preoperatively. Pedunculated GIST of the lesser omentum is very rare. It requires careful follow-up.
