By immunohistochemical examination (Fig. 3), the tumor was strongly positive for HMB-45, focally positive for c-Kit (CD117), and negative for vimentin, S-100, AE1/AE3, CK-7, CK-18, CD-10, RCC antigen, CgA, DOG-1, EMA, smooth muscle actin (SMA), and synaptophysin. The gene discussed is KIT; the disease is neoplasm.