Clinicopathological Features Of Gastric Stromal Tumors

Objective: Gastrointestinal stromal tumors(GISTs) are the most common mesenchymal neoplasms of the gastrointestinal (GI) tract.Over the last 10 years, scientific knowledge on GISTs has dramatically progressed. During this period, this distinct disease entity was identified under various acronyms (GIST remaining the most commonly used). A great majority of GISTs occur in the stomach (60~70%). The aim of this study was to evaluate the morphologic and immunohistochemical features of gastric stromal tumors (GSTs) and to explore the reference parameters for malignancy.Methods: Ninety-nine(99) cases of primary GSTs were distinguished from a group of gastrointestinal mesenchymal tumors by use of a panel of antibodies such as GDI 17, CD34, SMA, S-100, ki67 by immunhistochemica] SABC method, their biologic were analyzed by the clinicopathological features and their follow-up data.Results: All patients aged range 12~77 years (mean 55.8 year), male 59 cases and female 40 cases; the tumors were situated in gastric fundus (29 cases), in gastric corpus (62 cases) and pylorus (8 cases). The most common symtoms were abdomen mass vague pain and gastrointestinal bleeding. Grossly, they were of soft consistency often with hemorrhage, cystification or necrosis. Microscopically, the tumors were composed of spindle cells (64 cases) or epithelioid cells (17 cases) and of both cells (18 cases), arranged in interlacing fasicles, diffusing sheets, pallisading, whirling, alveolar and giant pseudo-rosette shapes. Tumor cells often had abundant cytoplasm with light to moderate eosinophilic or slight basophilic in staining, the nuclei generally showed spindle,blunted ends, round or signet in shape with nucleoli. Immuohistocheniically, CD117 and CD34 showed diffuse strong expression, the positive rates were 90. 9% and 74. 7% respectively, SMA, S-100 showed focal expression, the posi live rates 15. 2% and 5. 1% , respectively, ki67 labeling i ndex>10% was 5. 1%. Fifty-two cases were potential malignancy, forty-seven cases were malignancy. Follow-up of 19 cases with potential malignancy found 17 cases alive. In the malignant group of 47 cases, 15 cases are alive. In this group, tumor over 5 cm in diameter, mitotic activity over 5/50HPE had significant differences among two groups. The date were analysed by univariate and multivariate statistical analysis using a computer program.The results showed that the'greatest diameter, tumor grade,mitotic count and complete resection are prognostic factors in univariate analysis. In multivariate analysis only the complete resection is a useful prognostic factor for planning further therapy.Conclusions: Gastric stromal tumors predominantly occurred in middle aged or old patients, the tumors had varied cell types and different arrangement, the immunohistochemical characters were positive for CD117and CD34, occasional positive for SMA, S-100, which were helpful to differentiate GST from leiomyomas and Schwannomas. Over 5cm in diameter and mitotic activity over 5/50HPE might be the potential malignant parameters, the greatest diameter, tumor grade, mitotic count and complete resection are prognostic factors in univariate analysis. In multivariate analysis only the complete resection is a useful prognostic factor for planning further therapy.