An Adult Gastric Duplication Cyst Mimicking a Gastrointestinal Stromal Tumor.

We herein describe a rare case of a 24-year-old man who presented with severe epigastralgia after consuming a considerable amount of broiled meat. Computed tomography revealed a cystic lesion adjacent to the distal stomach, with high intensity on T2-weighted magnetic resonance imaging. Upper endoscopy showed a cystic mass measuring 6 cm in diameter, mimicking a submucosal tumor adjacent to the pyloric valve, with duodenum invagination, characteristic of ball valve syndrome.