Histopathological findings and immunohistochemical staining of the small intestine tumor. (A) The resected mass shows a tumor with hypercellularity and spindle-shaped cells. The mitotic index is 70 per 50 high-power fields (hematoxylin and eosin stain, scale bar: 50μm). Immunohistochemical stain for c-KIT (B) shows diffuse staining of the cell membrane. CD34 (C) and S-100 (D) staining reveals negativity.