Detection of c-kit and PDGFRA mutation for disease diagnosis and management of gastrointestinal stromal tumor

In contrast to epithelial tumors, gastrointestinal stromal tumor (GIST) is a tumor that originates from mesenchymal cells in the gastrointestinal tract. Although this tumor is a special entity and is the most common type of mesenchymal tumor amongst other types, GIST share similar clinical features with other types of mesenchymal tumors in the gastrointestinal tract. The tumors have similar clinical symptoms, like abdominal pain, bleeding, and mass or obstruction in larger tumor sizes. These similar clinical symptoms are one of the complicating factors in establishing the diagnosis of GIST, which differentiates it from other mesenchymal tumors of the digestive tract. Because GIST are known to not respond to chemotherapy used in the management of most malignancies, there is a need to differentiate between GIST and other mesenchymal tumors in the gastrointestinal tract. This review discusses the utilization of gene mutations known to be present only in GISTs, namely the c-kit and PDGFRA genes, through the detection of CD117 and DOG-1 proteins that are expressed due to the presence of these GIST-specific gene mutations, using the immunohistochemical examination. The prevalence of positive expression on immunohistochemical examination of CD117 and DOG-1 in GIST makes immunohistochemical examination the gold standard of GIST diagnosis. The diagnosis of GIST using CD117 and DOG-1 immunohistochemistry, as well as knowledge about GIST-specific gene mutations, is very useful for determining effective and efficient therapy.