Treatment of Zollinger Ellison syndrome -

• GISTs: MC mesenchymal tumor of the GI tract • MC primary site for GIST: Stomach (60–70%) > small bowel (20–25%) > colorectum and esophagus (5% each). • Most GISTs are positive for CD-117 (95%), BCL-2 (80%), CD-34 (70%) • Types: Spindle cell (70%) and Epitheloid (30%) Pathology: • Arise from the muscularis propria and most likely originate from the cells of Cajal • Expression of the receptor tyrosine kinase KIT (CD 117), 5% express platelet derived growth factor receptor alpha (PDGFRA). • PDGFRA mutations in GIST appear to confer a very favorable prognosis with low risk of recurrence. • Spindle cell 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-theta Clinical 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 Diagnosis: • CT: IOC for evaluation of primary tumor and accurate staging • PET-CT: Gold standard for recurrent GIST • Percutaneous or endoscopic biopsy should only be performed if the results would obviate the need for surgeryQ. Treatment: • Bleeding manifestation is the MC indication for surgery. • GIST should be treated with segmental resectionQ (margins of 1cm) • LN metastasis are uncommon, regional lymphadenectomy is not recommended • Intraoperative incisional biopsy prior to resection should be avoided, because it risks tumor spillage • Imatinib (selective inhibitor of type 3 tyrosine kinase KIT), is approved for use in CD117-positive unresectable and metastatic GISTs. • Functional imaging of GIST with 18FDG-PET scanning represents a useful diagnostic modality for early-response assessment with imatinib therapy. • Sunitinib 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: Liver, 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.