c-kitMutation and Immunohistochemical Expression in Gastrointestinal Stromal Tumors

ABSTRACT

BACKGROUND: Gastrointestinal stromal tumor (GIST) is the most common non-epithelial neoplasm arising in the gastrointestinal tract. The aim of this study is to investigate the correlation among the clinicopathologic features, presence of c-kit mutation, and immunohistochemical expression of c-kit in 61 cases of GISTs. METHODS: We divided the GISTs into three groups as benign, boderline and malignant, according to histologic grade. Exon 11 of the c-kit was amplified by PCR and sequenced. We performed immunohistochemical study for CD117, CD34, vimentin, SMA, desmin, and S-100 protein. RESULTS: Twenty-one cases were diagnosed as benign GISTs, 14 cases as borderline GISTs, and 26 cases as malignant GISTs. The shape, atypia, cellularity, and necrosis showed good correlations with the histologic grades of the GISTs.Mutations of exon 11 of the c-kit were detected in 3 benign GISTs, 4 borderline GISTs, and 13(%) malignant GISTs. Sequence analysis confirmed the deletion mutation (n=16) and the singlebase pair mutation (n=4). The immunohistochemical stainings showed myogenic differentiation(n=20), neurogenic differentiation (n=15), and neither myogenic or neurogenic differentiation(n=34). CONCLUSIONS: The GIST is the primitive mesenchymal tumor capable of divergent differentiation, and the mutation of the c-kit is a good parameter for the malignant GIST.