RESUMO
<p><b>OBJECTIVE</b>To investigate the clinicopathological characteristics, and treatment of malignant gastrointestinal stromal tumors (MGIST).</p><p><b>METHODS</b>Immunohistochemistry was used to detect CD117, CD34, S100, vimentin and SMA expressions. The postoperative curative effect was compared between the patients with or without imatinib treatment.</p><p><b>RESULTS</b>Radical resection was performed in 60 cases. Twenty-two tumors with a mean diameter of 5.3 cm were potentially malignant, and 38 tumor with a mean diameter of 9.2 cm were malignant. Microscopical examination revealed haemorrhagia or necrosis, abundant tumor cells, heteromorphism and caryocinesia of the tumors. 54 Cases were CD117 positive, 53 cases CD34 positive, 48 cases vimentin positive, 27 cases S100 positiveì16 cases SMA positive. The two-year recurrence rate was 80.5% in the patients without postoperative imatinib treatment, significantly higher than 21.1% in the patients with postoperative imatinib treatment(P< 0.05).</p><p><b>CONCLUSIONS</b>CD117 and CD34 markers are most valuable diagnostic indexes of MGIST, but its final diagnosis depends on pathology. Postoperative imatinib treatment is most effective to control recurrence and metastasis.</p>