Klin Onkol 2006; 19(4): 201-211.
Summary
Gastrointestinal stromal tumor is the most frequent mesenchymal tumor of the alimentary tract, currently being defined as a tumor composed of spindle and/or epithelioid cells presumably differentiating towards interstitial cells of Cajal. The majority of these tumors are KIT-immunoreactive and almost all carry mutated c-kit or PDGFRA gene encoding two transmembrane class III tyrosin kinases. The most frequent location of gastrointestinal stromal tumor is the stomach followed by other sites of gastrointestinal tract. Occasional sites of occurrence are mesentery, omentum, retroperitoneum, gallbladder, urinary bladder, pancreas and vagina. Light microscopic examination of slides stained with hematoxylin and eosin is highly reliable in most cases. Useful ancillary diagnostic techniques are immunohistochemical investigation with antibodies against KIT protein (CD117), and detection of mutations of either c-kit or PDGFRA genes. Nevertheless, negative results do not exclude histologically proven diagnosis. All gastrointestinal stromal tumors should be regarded as potentially malignant with risk of aggressive behavior being determined on the basis of mitotic count and the largest diameter of the tumor. Mutational status of the neoplasm serves as a predictor of therapeutic response to imatinib mesylate.
