Histopathologic investigations revealed that the resected mass was a composite of that CD117(+), CD34(+), desmin(−), DOG-1(+), Ki-67(+5%), S-100(−), SDH-B(+), and SMA(−), all of which are consistent with GIST tumor (Figure 4). The gene discussed is KIT; the disease is gastrointestinal stromal tumor.