| Background and objectiveGastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal, and its incidence is 10~20/million. GIST has been suggested that it origin of pluripotential stem cells. It may occur in the entire length of the gastrointestinal (GI) tract including the omentum and mesentery adjacent to the stomach and intestines. In the earlier literature, GIST was diagnose as smooth muscle tumor, leiomyoma, leiomyoblastoma, and leiomyosarcoma. The recent understanding on its molecular pathogenesis, namely common presence of activating mutations in the gene encoding KIT, may have significant clinical importance, making it necessary to accurately define and clinically diagnose this tumor and separate it from other mesenchymal tumors of the abdomen.The KIT protein (CD117), the c-kit pro-oncogene protein, is a transmembrane growth factor receptor for stem cell factor (SCF), and belongs to the family of receptor tyrosine kinases. It may present in hematopoietic stem cells, mast cells, melanocytes, and interstitial cell of cajal in the GI tract. CD117 is a sensitive and specific marker for GIST, and is capital to diagnosis. Approximately 60-70% of all GISTs are positive for CD34, the hematopietic progenitor cell is important for GIST to be distinguished from leiomyoma, leiomyosarcoma and Schwann cell tumor. Approximately 10% GISTs have cytoplasmic and nuclear S-100 protein positivity. The combination of KIT and S-100 protein positivity separates GIST immunohistochemically from gastrointestinal Schwann cell tumor.At present, the prediction of malignancy of GISTs is often difficult, and there is not a uniform and unambiguous criteria for this distinction. It was reported that the important prognostic variables included age, sex, tumor location, size, tumor necrosis, histological type, cellularity with tumor cell, mitotic activity, CD34 and S-100 expression, complete resection, metastatic or recurrent tumor, infiltrative growth pattern, involved organ resection and other primary tumors, and so on. Part I Gastrointestinal stromal tumors: diagnosis and a clinicopathologic studyThe clinicolpathologic features of 32 cases of primary GIST were analysed. The purpose of this experiment is to study the diagnosis, pathomorphological and immunohistochemical features of GIST and to explore the reference parameters for malignancy. It may provide references for diagnosis and treatment of GIST. Part II Analysis of Prognostic Factors With Gastrointestinal stromal tumorA retrospective review was performed of 46 GIST patients treated between Jan. 1993 and Dec.2000. The purpose is to investigate the clinicopathologic features and prognostic factors of GIST.Materials and methods Part I Gastrointestinal stromal tumors: diagnosis and a clinicopathologic studySpecimens were obtained from 54 patients who suffered from gastrointestinal mesenchymal tumors in the Second Affiliated Hospital of Medical College of Zhejiang University from January 1994 to December 2000. Light microscopy was used to study the morphologic characteristics of these tumors, and the expression of GDI 17, CD34 and S-100 with EnVision immunohistochemical method.32 cases of GIST were distinguished from gastrointestinal mesenchymal tumors, and the clinicolpathologic features of them were analysed. The data were analyzed using chi-square test by SPSS 11.0 softwares. P<0.05 was considered statistically significant. Part II Analysis of Prognostic Factors With Gastrointestinal stromal tumorA retrospective review was performed of 46 GIST patients treated in the Second Affiliated Hospital of Medical College of Zhejiang University from January 1993 to December 2000. Kaplan-Meier method, Log-rank test and Cox proportional hazards model were used to analyse the prognostic variables of GIST by SPSS 11.0 softwares. P<0.05 was considered statistically significant.ResultsPart I Gastrointestinal stromal tumors: diagnosis and a clinicopathologic study1.Immunohistochemical expressions of GISTImmunohisto...
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