Histological and Immunological Evaluation of Gastrointestinal Stromal Tumors

Background: gastrointestinal stromal tumors (gists) constitutethe majority of gastrointestinal mesenchymal tumors.they usually express a proto-oncogen protein called cd 117detected by immunohistochemistry. this study investigated thedifferentiation of gists as well as the risk of aggressive behaviorsin gists from surgically-treated patients in university affiliatedhospitals.methods: the clinicopathologic, histomorphologic and immunohistochemicalfeatures of 36 gists of patients referring to twolarge general hospitals in the last 13 years were examined.results: the gists occurred in 36 patients (41.6% male and58.4% female) aging 15 to 89 years. 50% of the cases were in thestomach, 30% in the small intestine and the remainder in thecolon and mesenter. the diameters of tumors were 0.7 to 30 emand mostly (60.6%) more than 5. 85% of tumor cells werespindle, 14% epithelioid, and the remainders were mixed. 36.1%of tumors showed mitotic counts> 5/50 hpf and 11.1 % less than5/50hpf. 33.3% of the tumors showed necrosis. 8 tumors hadmalignant behavior during 13-yrs follow up. immunoreactivityfor c-kit, sma, chromogranin, synaptophysin, desmin and s100were 83.3%, 69.4%, 44.4%, 41.6%, 50% and 0%, respectively.the decreasing rank order of differentiation forms were neural,smooth muscle, dual and null. most of our tumors were in highrisk group and most of the high risks were intestinal with neurogenicdifferentiation.conclusion: immunostaining including c-kit is necessary tostudy the differentiation of gastrointestinal stromal tumors.