Objective: To determine the prevalence of CD117, CD34 and DOG-1 reactive in spindle and epithelioid cell tumors of
gastrointestinal tract.
Materials and Methods: 82 paraffin blocks of patients from archive of the Department of Anatomical Pathology. Paraffin
blocks were searched along with clinical history of gender, age, primary location of the tumor, tumor size, mitotic count and previous pathologic diagnosis. Immunohistochemical studies for CD117, CD34 and DOG-1 were performed. Cases were diagnosed as GIST when >2 IHC stainings were positive. Risk assessment of GIST was grouped according to the revised
National Institutes of Health [NIH] Risk criteria.
Results: Out of 82 cases, 44 had primarily been diagnosed as GIST whereas the remaining had diagnosis of other mesenchymal tumors. The most frequent positive IHC stainings were DOG-1 and CD117 (56 cases or 68.3%), followed by CD34 (47 cases or 57.3%). Overall, 56 cases (including 44 cases with primary diagnosis of GIST) were diagnosed as GIST by positive staining of 2 or 3 markers. We categorized our patients with GIST into risk groups and found that 28 cases (50.0%) were in the high-risk group.
Conclusion: The present study, all 56 cases of GIST reveals positive CD117 (100%) and DOG-1 (100%). Forty-six out of
56 cases of GIST are also positive CD34 (82.1%). Then CD34 immunohistochemical marker is a supporting marker, using with CD117 or DOG-1 for diagnosis of GIST.

Keywords: Gastrointestinal stromal tumor, CD117, DOG-1, CD34, Gastrointestinal tract, Spindle cell, Epithelioid cell