E2357. Beyond the Stomach: The Many Faces of GIST
  1. Catherine Naidoo; University Health Network
  2. Ciara O'Brien; University Health Network
Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumour of the gastrointestinal tract, arising from the interstitial cells of Cajal. While the majority are indolent, a percentage are malignant with larger tumor size often associated with poorer prognosis. On cross sectional imaging GISTs are typically seen as circumscribed submucosal and exophytic lesions which may have areas of central necrosis. Although most commonly occurring in the stomach followed by the small bowel, GISTs can occur anywhere along the gastrointestinal tract. GISTs in uncommon locations may be difficult to distinguish on imaging from other gastrointestinal tract tumours and large lesions can be difficult to distinguish from tumours arising from other organs. It is important that the radiologist is aware of the variable locations in which GIST may occur to aid in providing an appropriate diagnosis.

Educational Goals / Teaching Points
Present a spectrum of cases of GISTs at typical and uncommon locations. Demonstrate the imaging findings of GISTs at multimodality cross sectional imaging which can lead the radiologist to the appropriate diagnosis, as well as illustrate typical and less common patterns of metastatic spread. At the end of this exhibit, the viewer will have an appreciation for the varying appearances of GIST, and have increased diagnostic acumen for suspected GIST particularly at less common locations.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Provide a multimodality pictorial review of GISTs at common and atypical sites including stomach, jejunum, pancreaticoduodenal, gastrooesophageal and anorectal GIST as well as illustrate typical and uncommon patterns of metastatic spread. Demonstrate key imaging characteristics of GIST on magnetic resonance imaging and computed tomography. Discuss an appropriate differential diagnosis particularly for tumors at less common locations

Although uncommon, GIST is the most common mesenchymal tumor of the gastrointestinal tract. While GIST may show typical imaging findings at common locations, it can occur in atypical locations and larger tumors in particular may be difficult to differentiate from lesions arising from other organs, which can result in a diagnostic challenge on the basis of imaging. It is important that the radiologist is aware of these variable locations to aid in providing an accurate differential.