small bowel (20-25%)> eolorectum and esophagus (5% each).Most GISTs are positive for CP-117 (95%), BCL-2 (80%). CD-34 (70%).* Types: Spindle cell (70%) and Epitheloid (30%)degPathology:* Arise from the muscularis propria and most likely originate from the cells of Cajaldeg* Expression of the receptor tyrosine kinase KIT (CD 117). 5% express platelet derived growth factor receptor alpha (PPGFRA)* P DC FRA mutations in GIST appear to confer a very favorable prognosis with low risk of recurrence.* Spindle ceil pattern (70%) of GIST is more common than epitheloid or round cell pattern (30%).* New tumor markers of GIST: DOG-1 (discovered on GIST-1) and protein kinase C-thetaClinical features:* Patients usually present after the fourth decade, with the mean age of 60 years at diagnosis.* MC presentations of gastric GISTs: GI bleeding and pain or dyspepsia.Carney triad* Association of extra-adrenal paragangliomas, pulmonary chondromas and multifocal GIST(r)Diagnosis:* CT: IOC for evaluation of primary tumor and accurate staging0* PET-CT: Gold standard for recurrent GIST0Percutaneous or endoscopic biopsy should only be performed if tbe results would obviate the need for surgervQ.Treatment:Bleeding manifestation is the MC indication for surgervQ.GIST should be treated with segmental resection0 (margins of 1cm)* LN metastasis are uncommon, regional lymphadenectomy is not recommended0* Intraoperative incisional biopsy prior to resection should be avoided, because it risks tumor spillage0* Imatinib (selective inhibitor of type 3 tyrosine kinase KIT ), is approved for use in CD 117-positive unresectable and metastatic GISTs.* Functional imaging of GIST with 18FDG-PET scanning represents a useful diagnostic modality forearly-response assessment with imatinib therapy0.* Sunitinib0 is used in imatinib-refractory disease.Prognosis:* Tumor size is a predominant factor for survival in surgical series for primary GIST.* MC sites of disease failure after complete resection: Liver0, omentum or peritoneal cavity.* Half to two third primaries will have disease failure within the liver and nearly 40% will have liver as the only site of failure. Generally hepatic involvement is multifocal.* Median time to recurrence after resection of primary GIST is 2 years.">