GIST : Gastro Intestinal Stromal Tumor
GISTs were misdiagnosed as smooth muscle
Originate from cells of Cajal
pacemaker
cells that are involved in the regulation of gut
motility
Characterized by expression of a tyrosine
50 y.o, woman,
small-bowel GIST
Histopathologic:
typical GIST
composed of
fascicles of
nondescript spindle
cells.
H and E stain:
The most common mesenchymal tumors to
arise from the gastrointestinal tract
40
–
70 years old
Male ≈ female
Approximately
Benign (70-80%)
Organ of origin
Stomach (60-70%) the most common site
Small intestine (20-30%)
Colon and rectum (5-10%)
Asymptomatic (incidentally on imaging,
surgery, autopsy)
Tumor induced: GI bleed, anemia
Secondary to mass effect
Abdominal discomfort
Palpable mass
Bowel obstruction and/or perforation
Contour -->
Growth pattern
Endoluminal
Exophytic
Mixed
Border
95% well defined
Enhancement pattern: depends on size
Heterogenous (Large)
Imaging modalities
Conventional
abdominal radiography, barium study
Ultrasound
CT scan
MRI
PET scan
GIST detectable:
Large enough (density, not specific)
Calcified (25% cases)
Rounded filling defect -> endoluminal mass
Typically hypoechoic
Peritoneal GIST. Axial contrast-enhanced CT scan in 65-year-old
male shows multiple heterogeneously
Common: liver and peritoneal cavity via
hematogenous spread and peritoneal seeding.
Occasional: soft tissues, lungs, and pleura
Marla et al:
Tumors that enhanced homogenously (nine out of 53 cases in their series) showed no metastases (2.6 years) as compared with those that enhanced
50-year-old woman with gastric
gastrointestinal
stromal tumor. Axial contrast-enhanced CT scan of liver reveals hypovascular (arrow) and hypervascular
Coronal
contrast-enhanced CT scan in a 39-year-old male
operated for gastric
GIST are the most common mesenchymal tumors of the digestive tract
The most common site is the stomach followed by the small intestine
Radiological features are intramural mass, exophytic large and heterogeneous contrast enhancement
Approximately 70-80% benign and 20-30% malignant
Malignant GIST are lesion > 5 cm, indistinct margins,
irregular surface, heterogeneous contrast enhancement, component necrotic-cystic, tissue invasion, hepatic
Kim JY, et al. Ectopic pancreas: CT findings with emphasis on
differentiation from small gastrointestinal stromal tumor and leiomyoma. Radiology. 2009 Jul;252(1):92-100.
Levy AD, Remotti HE, Thompson WM, Sobin LH, Miettinen M.
Gastrointestinal stromal tumors: radiologic features with pathologic correlation. RadioGraphics 2003; 23:283–304.
Rana R, et al. Calcified gastrointestinal stromal tumor of the sigmoid
colon mimicking inspissated barium on CT. AJR Am J Roentgenol. 2006 Sep;187(3):W322-3.
Sripathi S, et al. CT features, mimics and atypical presentations of
gastrointestinal stromal tumor (GIST). Indian J Radiol Imaging 2011;21:176-81.
