Background: Most common mesenchymal tumors of GI tract Risk assessment uses: Tumor size Mitotic rate Anatomic location Tumor rupture Significantly increases recurrence risk. Gastric GIST generally have better prognosis than non-gastric GIST. For example, a >10 cm gastric tumor with >5 mitoses/50 HPF has 34% metastasis risk, while the same parameters in small bowel GIST carry 71-90% risk. Work up: Histology + IHC: Confirm GIST with positive KIT and/or DOG1 immunostaining. Imag