This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Treatment of Zollinger Ellison syndrome - \nSelect and explain. \nA. Total gastrectomy with removal of tumour, B. Partial gastrectomy, C. Excision of tumour alone, D. H2, receptor antogonist', 'role': 'user'}, {'content': 'Answer: C \nExplanation: • GISTs: MC mesenchymal tumor of the GI tract\n• MC primary site for GIST: Stomach (60–70%) > small bowel (20–25%) > colorectum and esophagus (5% each).\n• Most GISTs are positive for CD-117 (95%), BCL-2 (80%), CD-34 (70%)\n• Types: Spindle cell (70%) and Epitheloid (30%)\nPathology:\n• Arise from the muscularis propria and most likely originate from the cells of Cajal\n• Expression of the receptor tyrosine kinase KIT (CD 117), 5% express platelet derived growth factor receptor alpha (PDGFRA).\n• PDGFRA mutations in GIST appear to confer a very favorable prognosis with low risk of recurrence.\n• Spindle cell pattern (70%) of GIST is more common than epitheloid or round cell pattern (30%).\n• New tumor markers of GIST: DOG-1 (discovered on GIST-1) and protein kinase C-theta\nClinical features:\n• Patients usually present after the fourth decade, with the mean age of 60 years at diagnosis.\n• MC presentations of gastric GISTs: GI bleeding and pain or dyspepsia.\nCarney triad\n• Association of extra-adrenal paragangliomas, pulmonary chondromas and multifocal GIST\nDiagnosis:\n• CT: IOC for evaluation of primary tumor and accurate staging\n• PET-CT: Gold standard for recurrent GIST\n• Percutaneous or endoscopic biopsy should only be performed if the results would obviate the need for surgeryQ.\nTreatment:\n• Bleeding manifestation is the MC indication for surgery.\n• GIST should be treated with segmental resectionQ (margins of 1cm)\n• LN metastasis are uncommon, regional lymphadenectomy is not recommended\n• Intraoperative incisional biopsy prior to resection should be avoided, because it risks tumor spillage\n• Imatinib\xa0(selective inhibitor of type 3 tyrosine kinase KIT), is approved for use in CD117-positive unresectable and metastatic GISTs.\n• Functional imaging of GIST with 18FDG-PET scanning represents a useful diagnostic modality for early-response assessment with imatinib therapy.\n• Sunitinib\xa0is used in imatinib-refractory disease.\nPrognosis:\n• Tumor size is a predominant factor for survival in surgical series for primary GIST.\n• MC sites of disease failure after complete resection: Liver, omentum or peritoneal cavity.\n• Half to two third primaries will have disease failure within the liver\xa0and nearly 40% will have liver as the only site of failure. Generally hepatic involvement is multifocal.\n• Median time to recurrence after resection of primary GIST is 2 years.', 'role': 'assistant'}]