Natural History of Exophytic Type Gastrointestinal Stromal Tumor: A Case Report

Abstract

Gastrointestinal stromal tumor (GIST) is the most common submucosal tumor of the stomach. GISTs are often detected by esophagogastroduodenal endoscopy. We have previously reported on endoscopically invisible medium-sized exophytic type GISTs. We present here a case of small exophytic GIST detected by transabdominal ultrasonography (TUS) in which the natural history of the tumor could be traced retrospectively through incidental findings obtained during follow-up for intraductal papillary mucinous neoplasm by magnetic resonance of imaging or computed tomography over about 10 years. The tumor appeared 7 years before its detection, and the doubling time was calculated as 6.9 years. In conclusion, low-risk exophytic GIST was estimated to have taken at least about 7 years to reach a size detectable by TUS.